Liquid crystal composition, reflective layer, method for producing reflective layer, and copolymer

ABSTRACT

A first object of the present invention is to provide a liquid crystal composition which has excellent planarity in a case of being formed into a coating film and is also capable of forming a reflective layer having excellent diffuse reflectivity. A second object of the present invention is to provide a reflective layer that is formed using the liquid crystal composition, as well as a method for producing a reflective layer. A third object of the present invention is to provide a copolymer that can be used as an alignment control agent for a liquid crystal compound. 
     The liquid crystal composition of the present invention includes a polymerizable liquid crystal compound and a copolymer having a predetermined structure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of PCT International Application No.PCT/JP2018/036854 filed on Oct. 2, 2018, which claims priority under 35U.S.C. § 119(a) to Japanese Patent Application No. 2017-192714 filed onOct. 2, 2017, The above application is hereby expressly incorporated byreference, in its entirety, into the present application.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a liquid crystal composition, areflective layer, a method for producing a reflective layer, and acopolymer.

2. Description of the Related Art

A cholesteric liquid crystalline phase is a liquid crystalline phase inwhich liquid crystal molecules are aligned in a helical manner and whichhas a periodic structure with a refractive index anisotropy in a helicalaxis direction, and has a property of reflecting light corresponding toa helical pitch on a plane perpendicular to the helical axis. In recentyears, a layer in which an alignment state of the cholesteric liquidcrystalline phase is fixed (hereinafter, also referred to as a “layerformed by fixing a cholesteric liquid crystalline phase”) has beenapplied to various fields such as a light reflecting plate and a screen.Due to the nature of the cholesteric liquid crystalline phase, eitherdextrorotatory circularly polarized light or levorotatory circularlypolarized light is selectively reflected in a case where light isincident from the normal direction of the surface of the layer formed byfixing a cholesteric liquid crystalline phase.

The layer formed by fixing a cholesteric liquid crystalline phase asdescribed above is formed, for example, by applying a liquid crystalcomposition containing a liquid crystal compound on a transparent basematerial to form a composition layer, and then fixing the liquid crystalcompound contained in the composition layer to a desired alignmentstate. At that time, the liquid crystal compound in the compositionlayer is aligned by receiving an alignment regulating force from thebase material interface and the air interface.

In addition, a compound containing a fluorine chain is generally knownas an alignment control agent for regulating the alignment on the airinterface side. For example, JP2006-016599A discloses an example inwhich uniaxial alignment of a polymerizable rod-like liquid crystalcomposition is controlled by using a (meth)acrylic copolymer having amolecular weight of 10,000 or more containing a mesogen moiety composedof two rings and a fluorine atom-containing moiety as an alignmentcontrol agent.

SUMMARY OF THE INVENTION

By the way, in recent years, attempts have been made to further improvethe diffuse reflectivity (property of reflecting light in variousdirections) of a layer formed by fixing a cholesteric liquid crystallinephase. For example, a method of making the direction of a helical axisof a liquid crystal compound aligned in a cholesteric liquid crystallinephase state non-uniform in a layer has been studied.

The present inventors formed a layer in which a cholesteric liquidcrystalline phase was fixed using a liquid crystal compositioncontaining the (meth)acrylic copolymer disclosed in the foregoingJP2006-016599A as an alignment control agent, and examined the diffusereflectivity thereof As a result, it was found that the diffusereflectivity did not satisfy the level required recently.

In addition, the present inventors also studied the performance of acoating film formed from the liquid crystal composition, and found thatit is necessary to further improve the planarity. In other words, thepresent inventors found that it is necessary to further suppress dryingunevenness and foreign matter that appear on the surface of the coatingfilm.

In view of the above circumstances, an object of the present inventionis to provide a liquid crystal composition which has excellent planarityin a case of being formed into a coating film and is also capable offorming a reflective layer having excellent diffuse reflectivity.

Further, an object of the present invention is to provide a reflectivelayer that is formed using the liquid crystal composition.

Further, an object of the present invention is to provide a method forproducing a reflective layer using the liquid crystal composition.

Further, an object of the present invention is to provide a copolymerthat can be used as an alignment control agent for a liquid crystalcompound.

As a result of extensive studies to achieve the foregoing objects, thepresent inventors have found that the foregoing objects can be achievedin a case where the liquid crystal composition contains a polymerizableliquid crystal compound and a copolymer having a predeterminedstructure. The present invention has been completed based on thesefindings.

That is, it has been found that the foregoing objects can be achieved bythe following configuration.

[1] A liquid crystal composition comprising:

a polymerizable liquid crystal compound; and a copolymer containing arepeating unit containing a group represented by General Formula (X1)which will be described later and a repeating unit derived from amonomer represented by General Formula (Y1) which will be describedlater, and having a weight-average molecular weight of less than 10,000.

[2] The liquid crystal composition according to [1], in which a contentof the repeating unit containing a group represented by General Formula(X1) is 25% by mass or more with respect to all the repeating units ofthe copolymer.

[3] The liquid crystal composition according to [1] or [2], in which therepeating unit containing a group represented by General Formula (X1) isa repeating unit derived from a monomer represented by General Formula(X2) which will be described later.

[4] The liquid crystal composition according to any one of [1] to [3],in which Z¹ is an alkyl group having 1 to 20 carbon atoms in which —CH₂—may be substituted with —O—, —CO—O—, —O—CO—, or —CO—, an alkenyl grouphaving 2 to 20 carbon atoms in which —CH₂— may be substituted with —O—or —CO—, a halogen atom, a cyano group, an acetyl group, a formyl group,a carboxy group, or a hydroxy group.

[5] The liquid crystal composition according to any one of [1] to [4],in which, in General Formula (Y1),

A^(l) and A² each independently represent a 1,2-phenylene group, a1,3-phenylene group, a 1,4-phenylene group, or a 1,4-cyclohexylenegroup, each of which may have a substituent,

X¹¹ represents a single bond, —O—, —CO—O—, or —O—CO—,

one or more of Y¹'s represent —CO—O— or —O—CO—, and

Z¹ represents an alkyl group having 1 to 8 carbon atoms in which —CH₂—may be substituted with —O—, —O—CO—O—, —O—CO—, or —CO—, an alkenyl grouphaving 2 to 8 carbon atoms in which —CH₂— may be substituted with —O— or—CO—, a halogen atom, or a cyano group.

[6] The liquid crystal composition according to any one of [1] to [5],in which a content of the repeating unit derived from a monomercontaining two or more polymerizable groups in the copolymer is lessthan 5 mol % with respect to all the repeating units of the copolymer.

[7] The liquid crystal composition according to any one of [1] to [6],in which the copolymer has a weight-average molecular weight of lessthan 9,000.

[8] The liquid crystal composition according to any one of [1] to [7],in which a content of the copolymer is 0.01% by mass or more and lessthan 5% by mass with respect to a content of the polymerizable liquidcrystal compound.

[9] The liquid crystal composition according to any one of [1] to [8],further comprising:

a chiral agent.

[10] A reflective layer obtained by polymerizing the liquid crystalcomposition according to any one of [1] to [9].

[11] A method for producing a reflective layer, comprising:

a step 1 of forming a composition layer on a transparent base materialnot subjected to a uniaxial alignment treatment using the liquid crystalcomposition according to any one of [1] to [9];

a step 2 of aligning a liquid crystal compound contained in thecomposition layer into

a cholesteric liquid crystalline phase state; and

a step 3 of fixing the cholesteric liquid crystalline phase after thestep 2.

[12] A copolymer comprising:

a repeating unit derived from a monomer represented by General Formula(X2) which will be described later; and

a repeating unit derived from a monomer represented by General Formula(Y1) which will be described later,

in which the copolymer has a weight-average molecular weight of lessthan 10,000.

According to the present invention, it is possible to provide a liquidcrystal composition which has excellent planarity in a case of beingformed into a coating film and is also capable of forming a reflectivelayer having excellent diffuse reflectivity.

Further, according to the present invention, it is possible to provide areflective layer that is formed using the liquid crystal composition.

Further, according to the present invention, it is possible to provide amethod for producing a reflective layer using the liquid crystalcomposition.

Further, according to the present invention, it is possible to provide acopolymer that can be used as an alignment control agent for a liquidcrystal compound.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the present invention will be described in detail.

The description of the constituent elements described below may be madebased on representative embodiments of the present invention, but thepresent invention is not limited to such embodiments.

In the present specification, the numerical range expressed by using“to” means a range including numerical values described before and after“to” as a lower limit value and an upper limit value, respectively.

Further, in the present specification, the term “(meth)acrylate” is anotation expressing both acrylate and methacrylate, the term“(meth)acryloyl group” is a notation expressing both acryloyl group andmethacryloyl group, and the term “(meth)acrylic” is a notationexpressing both acrylic and methacrylic.

Liquid Crystal Composition

A feature of the liquid crystal composition according to the embodimentof the present invention is that it contains a copolymer which will bedescribed later (hereinafter, also referred to as a “specificcopolymer”). Due to including the specific copolymer, the liquid crystalcomposition according to the embodiment of the present invention hasexcellent planarity in a case of being formed into a coating film and isalso capable of forming a reflective layer having excellent diffusereflectivity.

Although the action mechanism of the present invention is not clear, thepresent inventors speculate as follows.

It is considered that, in a case where a composition layer of a liquidcrystal composition containing a specific copolymer and a liquid crystalcompound is formed on a base material, the specific copolymer is likelyto be unevenly distributed at the interface on the air interface sidedue to the presence of a repeating unit containing a group representedby General Formula (X1) which will be described later, and controls thealignment of the liquid crystal compound from the air interface side. Inaddition, it is considered that a repeating unit derived from a monomerrepresented by General Formula (Y1) which will be described later in thespecific copolymer has a structure in which a mesogen moiety containedin the repeating unit is easily movable and has excellent compatibilitywith a liquid crystal compound, due to structural characteristicsthereof. It is considered that, due to the synergism of these actionmechanisms, the liquid crystal compound is controlled in alignment bythe copolymer, and therefore the direction of the helical axis of thehelically aligned liquid crystal compound becomes non-uniform in thelayer, in a case where the liquid crystal compound in the compositionlayer is aligned into a cholesteric liquid crystalline phase state.

As a result, the layer formed by fixing a cholesteric liquid crystallinephase (that is, the layer in which the alignment state is fixed(hereinafter, also referred to as “CL layer”) has a cholesteric liquidcrystal structure, and the cholesteric liquid crystal structure gives astripe pattern of a bright portion (continuous line) and a dark portion(continuous line) in a cross-sectional view of the CL layer observed bya scanning electron microscope (SEM), and therefore has a region inwhich the angle between the normal of a line formed by at least one darkportion and the surface of the CL layer periodically or irregularlychanges (note that the region in which the angle between the normal of aline formed by at least one dark portion and the surface of the CL layerperiodically changes can be confirmed in a cross-sectional SEM image,for example, as a region in which the bright portion and the darkportion have a wave-like structure). Therefore, light incident from thenormal direction of the CL layer is reflected by the CL layer, and thelight can be diffusely reflected in various directions, not in limiteddirections.

On the other hand, in a case where the direction of the helical axis ofthe helically aligned liquid crystal compound is uniform in the layer inthe state of the cholesteric liquid crystalline phase, the cholestericliquid crystal structure gives a stripe pattern of a bright portion(continuous line) and a dark portion (continuous line) in across-sectional view of the CL layer observed by a scanning electronmicroscope, and therefore both the bright portion and the dark portionare linear so as to be parallel to the surface of the CL layer.Therefore, in a case where light is incident from the normal directionof the CL layer, the light is reflected in the normal direction, but ishardly reflected in the oblique direction, which results in poor diffusereflectivity.

In addition, according to the foregoing specific copolymer, it has alsobeen confirmed that the planarity of the coating film of the compositionlayer of the liquid crystal composition is improved owing to the factthat the specific copolymer has a weight-average molecular weight ofless than a predetermined value and the fact that the specific copolymercontains a repeating unit containing a group represented by GeneralFormula (X1). In particular, as will be described later, it has beenconfirmed that, in a case where the content of the repeating unitcontaining a group represented by General Formula (X1) is 25% by masswith respect to all the repeating units of the specific copolymer, notonly the planarity of the composition layer of the liquid crystalcomposition is excellent, but also the diffuse reflectivity of thereflective layer is more excellent.

(Specific Copolymer)

Hereinafter, the specific copolymer will be described. The specificcopolymer contains a repeating unit containing a group represented byGeneral Formula (X1) which will be described later and a repeating unitderived from a monomer represented by General Formula (Y1) which will bedescribed later, and has a weight-average molecular weight of less than10,000.

Hereinafter, each of repeating units contained in the specific copolymerwill be described.

<Repeating Unit Containing Group Represented by General Formula (X1)>

The specific copolymer contains a repeating unit containing a grouprepresented by General Formula (X1).

Hereinafter, General Formula (X1) will be described.

* —L¹¹—CF₂X^(a)   (X1)

In Formula (X1), L¹¹ represents a single bond or a perfluoroalkylenegroup having 1 to 6 carbon atoms which may contain —O—. Theperfluoroalkylene group having 1 to 6 carbon atoms which may contain —O—and is represented by L¹¹ may be linear or branched. Examples of thebranched perfluoroalkylene group having 1 to 6 carbon atoms which maycontain —O— and is represented by L¹¹ include, in a CF₂CF₂OCF(CH₃)—,—CF(CF₃)CF₂CF₂—, and —CF₂CF₂CF(CF₃)—.

As the perfluoroalkylene group having 1 to 6 carbon atoms which maycontain —O— and is represented by L¹¹, a perfluoroalkylene group having1 to 6 carbon atoms is preferable, and a perfluoroalkylene group having4 to 6 carbon atoms is more preferable.

X^(a) represents a hydrogen atom or a fluorine atom. X^(a) is preferablya fluorine atom.

* represents a bonding position.

In a case where X^(a) represents a hydrogen atom, L¹¹ is preferably aperfluoroalkylene group having 1 to 6 carbon atoms which may contain—O—.

The repeating unit containing a group represented by General Formula(X1) is preferably a repeating unit derived from a monomer representedby Formula (X2).

In General Formula (X2), R¹¹ represents a hydrogen atom or a methylgroup. R¹¹ is preferably a hydrogen atom.

R¹² represents a monovalent group including the group represented byGeneral Formula (X1).

The monovalent group including the group represented by General Formula(X1), which is represented by R¹², is not particularly limited, andexamples thereof include General Formula (X3).

* —L¹²—L¹¹—CF₂X^(a)   (X3)

In General Formula (X3), L¹² is a single bond or an alkylene grouphaving 1 to 30 carbon atoms in which —CH₂— may be substituted with —O—.The number of carbon atoms in the alkylene group having 1 to 30 carbonatoms in which —CH₂— may be substituted with —O—, which is representedby L¹², is preferably 1 to 20 and more preferably 1 to 10. The alkylenegroup may be linear, branched, or cyclic. L¹² may further have asubstituent. Examples of the substituent include a hydroxy group.

In General Formula (X3), L¹¹ and X^(a) each have the same definition asL¹¹ and X^(a) in General Formula (X1), and the suitable aspects thereofare also the same.

In General Formula (X3), * represents a bonding position.

From the viewpoint of reducing the surface energy of the liquid crystalcomposition and enhancing the effects of the present invention, themonomer represented by General Formula (X3) is preferably a monomerrepresented by General Formula (X4).

In General Formula (X4), R¹¹ represents a hydrogen atom or a methylgroup. R¹¹ is preferably a hydrogen atom.

ma represents an integer of 0 or more. The upper limit of ma is, forexample, 20 or less. ma is preferably an integer of 1 to 10, morepreferably an integer of 1 to 6, and still more preferably an integer of1 to 4.

na represents an integer of 1 to 6. na is more preferably an integer of3 to 5.

X^(a) represents a hydrogen atom or a fluorine atom. X^(a) is preferablya fluorine atom.

Examples of the monomer represented by General Formula (III) include2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3,3 -pentafluoropropyl(meth)acrylate, 2-(perfluorobutyl)ethyl (meth)acrylate,2-(perfluorohexyl)ethyl (meth)acrylate, 2-(perfluoroheptyl)ethyl(meth)acrylate, 2-(perfluoro-3-methylbutyl)ethyl (meth)acrylate,2-(perfluoro-5-methylhexyl)ethyl (meth)acrylate,1H,1H,3H-tetrafluoropropyl (meth)acrylate, 1H,1H,5H-octafluoropentyl(meth)acrylate, 1H,1H,7H-dodecafluoroheptyl (meth)acrylate,1H-1-(trifluoromethyl)trifluoroethyl (meth)acrylate,1H,1H,3H-hexafluorobutyl (meth)acrylate,3-perfluorobutyl-2-hydroxypropyl (meth)acrylate,3-perfluorohexyl-2-hydroxypropyl (meth)acrylate, 3-(perfluoro-3-methylbutyl)-2-hydroxypropyl (meth)acrylate, and3-(perfluoro-5-methylhexyl)-2-hydroxypropyl (meth)acrylate.

The content of the repeating unit containing a group represented byGeneral Formula (X1) in the specific copolymer (in a case where thereare a plurality of repeating units containing a group represented byGeneral Formula (X1), the total content of the plurality of repeatingunits) is, for example, 5% by mass or more with respect to all therepeating units of the specific copolymer, and is preferably 25% by massor more from the viewpoint that the composition layer of the liquidcrystal composition has more excellent planarity and the reflectivelayer has more excellent diffuse reflectivity. The upper limit value ofthe content of the repeating unit containing a group represented byGeneral Formula (X1) is, for example, 70% by mass or less and preferably60% by mass or less with respect to all the repeating units of thespecific copolymer.

<Repeating Unit Derived from Monomer Represented by General Formula(Y1)>

In Formula (Y1), R¹ represents a hydrogen atom or a methyl group. R¹ ispreferably a hydrogen atom.

R² represents —O— or —NR³— where R³ represents a hydrogen atom or analkyl group having 1 to 3 carbon atoms. R² is preferably —O—.Incidentally, R³ is preferably a hydrogen atom.

L¹ represents an alkylene group having 1 to 20 carbon atoms in which—CH₂— may be substituted with —O—, —S—, or —CO—. In addition, in L¹, theposition adjacent to X¹ is preferably a carbon atom.

The number of carbon atoms in the alkylene group having 1 to 20 carbonatoms in which —CH₂— may be substituted with —O—, —S—, or —CO—, which isrepresented by L¹, is not particularly limited, but is preferably 1 to15, more preferably 1 to 10, and still more preferably 1 to 6.

In particular, the alkylene group having 1 to 20 carbon atoms in which—CH₂— may be substituted with —O—, —S—, or —CO—, which is represented byL¹, is preferably an alkylene group having 1 to 10 carbon atoms and morepreferably an alkylene group having 1 to 6 carbon atoms.

The alkylene group having 1 to 20 carbon atoms in which —CH₂— may besubstituted with —O—, —S—, or —CO—, which is represented by L¹, mayfurther have a substituent.

X¹ and Y¹ each independently represent a single bond, —O—, —CO—O—,—O—CO—, —O—CO—O—, —O—CH₂, —CH₂—O—, —C═N—, —N═N—, —CO—O—CH₂CH₂, or—CH₂CH₂—CO—O—.

X¹ is preferably a single bond, —O—, —CO—O—, or —O—CO—, more preferablya single bond or —O—, and still more preferably —O— from the viewpointthat the diffuse reflectivity of the reflective layer is more excellent.

Y¹ is preferably a single bond, —CO—O—, or —O—CO— from the viewpointthat the diffuse reflectivity of the reflective layer is more excellent,and it is preferred that one or more of Y¹'s represent —CO—O— or —O—CO—.

A¹ and A² each independently represent a phenylene group, acyclohexylene group, or a naphthylene group, each of which may have asubstituent.

In particular, from the viewpoint that the diffuse reflectivity of thereflective layer is more excellent, A¹ is preferably a 1,2-phenylenegroup, a 1,3-phenylene group, a 1,4-phenylene group, or a1,4-cyclohexylene group, each of which may have a substituent, and morepreferably a 1,4-phenylene group which may have a substituent.

In particular, from the viewpoint that the diffuse reflectivity of thereflective layer is more excellent, A² is preferably a 1,2-phenylenegroup, a 1,3-phenylene group, a 1,4-phenylene group, or a1,4-cyclohexylene group, each of which may have a substituent, and morepreferably a 1,4-phenylene group which may have a substituent.

The substituents that A¹ and A² may have are not particularly limited,and examples thereof include an alkyl group having 1 to 20 carbon atomsin which —CH₂— may be substituted with —O—, —CO—O—, or —O—CO—.

Z¹ represents an alkyl group having 1 to 20 carbon atoms in which —CH₂—may be substituted with —O—, —CO—O—, —O—CO—O—, or —CO—, an alkenyl grouphaving 2 to 20 carbon atoms in which —CH₂— may be substituted with —O—or —CO—, a halogen atom, a cyano group, an acetyl group, a formyl group,a carboxy group, a hydrogen atom, or a hydroxy group.

The number of carbon atoms in the alkyl group having 1 to 20 carbonatoms in which —CH₂— may be substituted with —O—, —CO—O—, —O—CO—, or—CO—, which is represented by Z¹, is preferably 1 to 10, more preferably1 to 8, and still more preferably 1 to 6. The alkyl group having 1 to 20carbon atoms in which —CH₂— may be substituted with —O—, —CO—O—, —O—CO—,or —CO—, which is represented by Z¹, may be linear, branched, or cyclic.

The alkyl group having 1 to 20 carbon atoms in which —CH₂— may besubstituted with —O—, —CO—O—, —O—CO—O—, or —CO—, which is represented byZ¹, is preferably an alkyl group having 1 to 10 carbon atoms in which—CH₂— may be substituted with —CO—O— or —O—CO—, and more preferably analkyl group having 1 to 8 carbon atoms in which —CH₂— may be substitutedwith —CO—O— or —O—CO—.

The number of carbon atoms in the alkenyl group having 2 to 20 carbonatoms in which —CH₂— may be substituted with —O— or —CO—, which isrepresented by Z¹, is preferably 2 to 10, more preferably 2 to 8, andstill more preferably 2 to 6. The alkenyl group having 2 to 20 carbonatoms in which —CH₂— may be substituted with —O— or —CO—, which isrepresented by Z¹, may be linear, branched, or cyclic.

The alkenyl group having 2 to 20 carbon atoms in which -CH₂- may besubstituted with —O— or —CO—, which is represented by Z¹, is preferablyan alkenyl group having 2 to 10 carbon atoms in which —CH₂— may besubstituted with —O— or —CO— and more preferably an alkenyl group having2 to 8 carbon atoms in which —CH₂— may be substituted with —O— or —CO—.

From the viewpoint that the diffuse reflectivity of the reflective layeris more excellent, Z¹ is preferably an alkyl group having 1 to 20 carbonatoms in which —CH₂— may be substituted with —O—, —CO—O—, —O—CO—, or—CO—, or —CO—, an alkenyl group having 2 to 20 carbon atoms in which—CH₂— may be substituted with —O— or —CO—, a halogen atom, a cyanogroup, an acetyl group, a formyl group, a carboxy group, or a hydroxygroup, and more preferably an alkyl group having 1 to 8 carbon atoms inwhich —CH₂— may be substituted with —CO—O— or —O—CO—, an alkenyl grouphaving 2 to 8 carbon atoms in which —CH₂— may be substituted with —O— or—CO—, a halogen atom, or a cyano group. That is, Z¹ is preferably otherthan a hydrogen atom.

In addition, the alkyl group having 1 to 20 carbon atoms in which —CH₂—may be substituted with —O—, —CO—O—, —O—CO—, or —CO—, and the alkenylgroup having 2 to 20 carbon atoms in which —CH₂— may be substituted with—O— or —CO—, each of which is represented by Z¹, may further have asubstituent.

m represents 0 or 1. m is preferably 1 from the viewpoint that thediffuse reflectivity of the reflective layer is more excellent.

n represents an integer of 2 to 4. n is preferably 2 or 3 from theviewpoint of more excellent planarity.

In General Formula (Y1), a plurality of A¹'s and a plurality of Y¹'s maybe the same as or different from each other.

Hereinafter, specific examples of the monomer represented by GeneralFormula (Y1) will be described, but the present invention is not limitedthereto.

The content of the repeating unit derived from General Formula (Y1) inthe specific copolymer (in a case where there are a plurality ofrepeating units derived from General Formula (Y1), the total content ofthe plurality of repeating units) is, for example, 40% by mass or more,preferably 60% by mass or more, and more preferably 65% by mass or morewith respect to all the repeating units of the specific copolymer. Theupper limit value of the content of the repeating unit derived fromGeneral Formula (Y1) is, for example, 95% by mass or less, preferably80% by mass or less, and more preferably 75% by mass or less, withrespect to all the repeating units of the specific copolymer.

<Other Copolymerization Components>

The specific copolymer may further contain a repeating unit derived fromother copolymerizable monomers, in addition to the repeating unitcontaining a group represented by General Formula (X1) and the repeatingunit derived from a monomer represented by General Formula (Y1).

The other copolymerizable monomers are not particularly limited, andexamples thereof include monomers such as BLEMMER E, BLEMMER PE90,BLEMMER PE200, BLEMMER PE350, BLEMMER AE90, BLEMMER AE200, BLEMMERAE400, BLEMMER P, BLEMMER PP1000, BLEMMER PP500, BLEMMER PP800, BLEMMERAP400, BLEMMER AP550, BLEMMER AP800, BLEMMER BMA, BLEMMER CHMA, BLEMMERCHA, BLEMMER LMA, BLEMMER GLM, AND BLEMMER LA (all of which aremanufactured by NOF Corporation), and monomers such as acrylic acid,4-acryloylmorpholine, N,N-diisopropylacrylamide, vinylpyrrolidone,hydroxyethyl methacrylate, and acetoacetoxyethyl methacrylate.

In a case where the specific copolymer contains a repeating unit derivedfrom other copolymerizable monomers, the content of the repeating unitderived from other copolymerizable monomers (in a case where there are aplurality of repeating units derived from other copolymerizablemonomers, the total content of the plurality of repeating units) is, forexample, 40% by mass or less, preferably 20% by mass or less, and morepreferably 10% by mass or less, with respect to all the repeating unitsof the specific copolymer.

In the specific copolymer, the content of the repeating unit derivedfrom a monomer containing two or more polymerizable groups is preferablyless than 5 mol % with respect to all the repeating units of thespecific copolymer, from the viewpoint that the mesogen moiety inGeneral Formula (Y1) is easily movable and the diffuse reflectivity ofthe reflective layer is more excellent. Here, the polymerizable groupmay be, for example, a polymerizable ethylenically unsaturated group ora ring polymerizable group. Specific examples of the polymerizable groupinclude a (meth)acryloyl group, a vinyl group, a styryl group, an allylgroup, an epoxy group, and an oxetane group.

It is preferable that General Formula (Y1) does not include two or morepolymerizable groups.

The weight-average molecular weight of the specific copolymer is lessthan 10,000. The weight-average molecular weight of the specificcopolymer is more preferably less than 9,000 from the viewpoint of moreexcellent planarity. The lower limit of the weight-average molecularweight of the specific copolymer is not particularly limited, but is,for example, 4,000 or more. The dispersity (Mw/Mn) is usually 1.0 to3.0, preferably 1.0 to 2.0, and more preferably 1.1 to 2.0.

The specific copolymer can be synthesized by a conventional method.

The specific copolymer may be used alone or in combination of two ormore thereof.

The content of the specific copolymer (in a case where there are aplurality of specific copolymers, the total content of the plurality ofspecific copolymers) in the liquid crystal composition is preferably0.01% by mass or more and less than 5% by mass, more preferably 0.01% to3% by mass, and still more preferably 0.05% to 3% by mass with respectto the content of the polymerizable liquid crystal compound contained inthe composition.

Polymerizable Liquid Crystal Compound

The liquid crystal composition contains a polymerizable liquid crystalcompound. In addition, the polymerizable liquid crystal compound isintended to refer to a liquid crystal compound having a polymerizablegroup. Hereinafter, the polymerizable liquid crystal compound that canbe used in the present invention will be described in detail.

The type of the liquid crystal compound is not particularly limited.

Generally, liquid crystal compounds can be classified into a rod type(rod-like liquid crystal compound) and a disc type (discotic liquidcrystal compound, disk-like liquid crystal compound) depending on theshape thereof. Further, the rod type and the disk type each have a lowmolecular weight type and a high molecular weight type. The highmolecular weight generally refers to having a degree of polymerizationof 100 or more (Polymer Physics-Phase Transition Dynamics, Masao Doi,page 2, Iwanami Shoten, 1992). Any liquid crystal compound can be usedin the present invention. Two or more liquid crystal compounds may beused in combination.

The liquid crystal compound has a polymerizable group. The type of thepolymerizable group is not particularly limited, and a functional groupcapable of addition polymerization reaction is preferable, and apolymerizable ethylenically unsaturated group or a cyclic polymerizablegroup is more preferable. More specifically, the polymerizable group ispreferably a (meth)acryloyl group, a vinyl group, a styryl group, anallyl group, an epoxy group, or an oxetane group, and more preferably a(meth)acryloyl group.

The number of polymerizable groups is not particularly limited, and maybe one or more. Above all, the number of the polymerizable groups ispreferably plural, more preferably 2 to 6, and still more preferably 2to 4 from the viewpoint that the diffuse reflectivity of the reflectivelayer is more excellent.

The molecular weight of the liquid crystal compound is not particularlylimited, but is preferably 400 or more and more preferably 700 or more.The upper limit of the molecular weight of the liquid crystal compoundis not particularly limited, but is often 2000 or less (especially in acase of a low-molecular weight type liquid crystal compound).

In addition, in a case where a rod-like liquid crystal compound is used,the liquid crystal compound is preferably a compound having four or morerings in the core portion of the mesogen group in the liquid crystalcompound, and more preferably a compound having five or more rings inthe core portion of the mesogen group in the liquid crystal compound,from the viewpoint of controlling the viscosity.

The liquid crystal compound is preferably a liquid crystal compoundrepresented by Formula (I) from the viewpoint that the reflective layerhas more excellent diffuse reflectivity.

In the formula,

A represents a phenylene group which may have a substituent or atrans-1,4-cyclohexylene group which may have a substituent,

L represents a single bond or a linking group selected from the groupconsisting of —CH₂O—, —OCH₂—, —(CH₂)₂O—CO—, —CO—O(CH₂)₂—, —CO—O—,—O—CO—, —O—CO—O—, —CH═CH—CO—O—, —O—CO—CH═CH—, —CH═N—N═CH—, —C═N—, —N═C—,—C≡C—, and —NH—,

m represents an integer of 3 to 12,

Sp¹ and Sp² each independently represent a single bond or a linkinggroup selected from the group consisting of a linear or branchedalkylene group having 1 to 20 carbon atoms and a group where one or twoor more —CH₂— in a linear or branched alkylene group having 1 to 20carbon atoms is substituted by —O—, —S—, —NH—, —N(CH₃)—, —CO—, —O—CO—,or —CO—O—, and

Q¹ and Q² each independently represent a hydrogen atom or apolymerizable group selected from the group consisting of groupsrepresented by Formulae (Q-1) to (Q-5), provided that one of Q¹ and Q²represents a polymerizable group.

A is a phenylene group which may have a substituent or atrans-1,4-cyclohexylene group which may have a substituent. In thepresent specification, the phenylene group is preferably a 1,4-phenylenegroup.

m pieces of A's may be the same as or different from each other.

In a case where a trans-1,4-cyclohexylene group which may have asubstituent is contained as A, from the viewpoint of more excellentdiffuse reflectivity of the reflective layer, upon assuming that thenumber obtained by dividing the number of trans-1,4-cyclohexylene groupswhich may have a substituent, which is represented by A, by m is definedas mc, a liquid crystal compound satisfying mc >0.1 is preferable, and aliquid crystal compound satisfying 0.4≤mc≤0.8 is more preferable.

Note that mc is a number represented by the following calculatingexpression.

mc=(the number of trans-1,4-cyclohexylene groups which may have asubstituent represented by A)/m

m represents an integer of 3 to 12, preferably an integer of 3 to 9,more preferably an integer of 3 to 7, and still more preferably aninteger of 3 to 5.

The substituent which the phenylene group and thetrans-1,4-cyclohexylene group in Formula (I) may have is notparticularly limited, and examples thereof include substituents selectedfrom the group consisting of an alkyl group, a cycloalkyl group, analkoxy group, an alkyl ether group, an amide group, an amino group, ahalogen atom, and a group formed by combining two or more of thesesubstituents. Examples of the substituent include substituentsrepresented by —CO—X³-Sp³-Q³ which will be described later. Thephenylene group and the trans-1,4-cyclohexylene group may have 1 to 4substituents. In a case of having two or more substituents, the two ormore substituents may be the same as or different from each other.

In the present specification, the alkyl group may be either linear orbranched. The number of carbon atoms in the alkyl group is preferably 1to 30, more preferably 1 to 10, and still more preferably 1 to 6.Examples of the alkyl group include a methyl group, an ethyl group, ann-propyl group, an isopropyl group, an n-butyl group, an isobutyl group,a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentylgroup, a neopentyl group, a 1,1-dimethylpropyl group, an n-hexyl group,an isohexyl group, a heptyl group, an octyl group, a nonyl group, adecyl group, an undecyl group, and a dodecyl group. The explanation ofthe alkyl group in the alkoxy group is also the same as the explanationon the foregoing alkyl group. Further, in the present specification,specific examples of the alkylene group in a case of being referred toas an alkylene group include divalent groups obtained by removing onehydrogen atom from each of the foregoing examples of the alkyl group.Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom, and an iodine atom.

In the present specification, the number of carbon atoms in thecycloalkyl group is preferably 3 or more and more preferably 5 or moreand is preferably 20 or less, more preferably 10 or less, still morepreferably 8 or less, and particularly preferably 6 or less. Examples ofthe cycloalkyl group include a cyclopropyl group, a cyclobutyl group, acyclopentyl group, a cyclohexyl group, a cycloheptyl group, and acyclooctyl group.

The substituent which the phenylene group and thetrans-1,4-cyclohexylene group may have is preferably a substituentselected from the group consisting of an alkyl group, an alkoxy group,and —CO—X³-Sp³-Q³. Here, X³ represents a single bond, —O—, —S—, or—N(Sp⁴-Q⁴)- or represents a nitrogen atom forming a ring structuretogether with Q³ and Sp³. Sp³ and Sp⁴ each independently represent asingle bond or a linking group selected from the group consisting of alinear or branched alkylene group having 1 to 20 carbon atoms and agroup where one or two or more —CH₂— in a linear or branched alkylenegroup having 1 to 20 carbon atoms is substituted with —O—, —S—, —NH—,—N(CH₃)—, —CO—, —O—CO—, or —CO—O—.

Q³ and Q⁴ each independently represent a hydrogen atom, a cycloalkylgroup, a group where one or two or more —CH₂— in a cycloalkyl group issubstituted with —O—, —S—, —NH—, —N(CH₃)—, —CO—, —O—CO—, or —CO—O—, orany polymerizable group selected from the group consisting of groupsrepresented by Formulae (Q-1) to (Q-5).

Specific examples of the group where one or two or more —CH₂— in acycloalkyl group is substituted with —O—, —S—, —NH—, —N(CH₃)—, —CO—,—O—CO—, or —CO—O— include a tetrahydrofuranyl group, a pyrrolidinylgroup, an imidazolidinyl group, a pyrazolidinyl group, a piperidylgroup, a piperazinyl group, and a morpholinyl group. Among them, atetrahydrofuranyl group is preferable, and a 2-tetrahydrofuranyl groupis more preferable.

In Formula (I), L represents a single bond or a linking group selectedfrom the group consisting of —CH₂O—, —OCH₂—, —(CH₂)₂O—CO—,—CO—O(CH₂H₂(₂—, —CO—O—, —O—CO—, —O—CO—O—, —CH═CH—CO—O—, —O—CO—CH═CH—,—CH═N—N—N═CH—, —C═N—, —N═C, —C≡C—, and —NH—. L is preferably —CO—O—,—O—CO—, or —NH—,

m pieces of L's may be the same as or different from each other.

Sp¹ and Sp² each independently represent a single bond or a linkinggroup selected from the group consisting of a linear or branchedalkylene group having 1 to 20 carbon atoms and a group where one or twoor more —CH₂— in a linear or branched alkylene group having 1 to 20carbon atoms is substituted with —O—, —S—, —NH—, —N(CH₃)—, —CO—, —O—CO—,or —CO—O—, Sp¹ and Sp² are each independently preferably a linking groupformed by combining one or two or more groups selected from the groupconsisting of a linear alkylene group having 1 to 10 carbon atoms towhich a linking group selected from the group consisting of —O—, —O—CO—,and —CO—O— is bonded to both terminals thereof, —O—CO—, —CO—O—, —O—, anda linear alkylene group having 1 to 10 carbon atoms, and more preferablya linear alkylene group having 1 to 10 carbon atoms to which —O— isbonded to both terminals thereof.

Q¹ and Q² each independently represent a hydrogen atom or apolymerizable group selected from the group consisting of groupsrepresented by Formulae (Q-1) to (Q-5), provided that either one of Q¹and Q² represents a polymerizable group.

The polymerizable group is preferably an acryloyl group (Formula (Q-1))or a methacryloyl group (Formula (Q-2)).

Specific examples of the liquid crystal compound include a liquidcrystal compound represented by Formula (1-11), a liquid crystalcompound represented by Formula (I-21), and a liquid crystal compoundrepresented by Formula (I-31). In addition to the foregoing compounds,known compounds such as a compound represented by Formula (I) inJP2013-112631A, a compound represented by Formula (I) in JP2010-070543A,a compound represented by Formula (I) in JP2008-291218A, a compoundrepresented by Formula (I) in JP4725516B, a compound represented byGeneral Formula (II) in JP2013-087109A, a compound described inparagraph [0043] of JP2007-176927A, a compound represented by Formula(1-1) in JP2009-286885A, a compound represented by General Formula (I)in WO2014/010325A, a compound represented by Formula (1) inJP2016-081035A, and a compound represented by Formulae (2-1) and (2-2)in JP2016-121339A can be mentioned.

Liquid Crystal Compound Represented by Formula (I-11)

In the formula, R¹¹ represents a hydrogen atom, a linear or branchedalkyl group having 1 to 12 carbon atoms, or —Z¹²-Sp¹²-Q¹²,

L¹¹ represents a single bond, —CO—O—, or —CO—,

L¹² represents —CO—O—, —O—CO—, —CO—NR²—, or —NR²—CO—,

R² represents a hydrogen atom or an alkyl group having 1 to 3 carbonatoms,

Z¹¹ and Z¹² each independently represent a single bond, —O—, —NH—,—N(CH₃)—, —S—, —CO—O—, —O—CO—, —O—CO—O—, —CO—NR¹², or —NR¹²—CO—,

Sp¹¹ and Sp¹² each independently represent a single bond, a linear orbranched alkylene group having 1 to 12 carbon atoms which may besubstituted with Q¹¹, or a linking group obtained by substituting one ormore —CH₂— in a linear or branched alkylene group having 1 to 12 carbonatoms which may be substituted with Q¹¹ with —O—, —S—, —NH—, —N(Q¹¹)—,or —CO—,

Q¹¹represents a hydrogen atom, a cycloalkyl group, a group where one ortwo or more —CH₂— in a cycloalkyl group are substituted with —O—, —S—,—NH—, —N(CH₃)—, —CO—, —O—CO—, or —CO—O—, or a polymerizable groupselected from the group consisting of groups represented by Formulae(Q-1) to (Q-5),

Q¹² represents a hydrogen atom or a polymerizable group selected fromthe group consisting of groups represented by Formulae (Q-1) to (Q-5),

l¹¹ represents an integer of 0 to 2,

m¹¹ represents an integer of 1 or 2,

n¹¹ represents an integer of 1 to 3, and

a plurality of R¹¹'s, a plurality of L¹¹'s, a plurality of L¹²'s, aplurality of l¹¹'s, a plurality of Z¹¹'s, a plurality of Sp¹¹'s, and aplurality of Q¹¹'s may be respectively the same as or different fromeach other.

The liquid crystal compound represented by Formula (I-11) contains atleast one -Z¹²-Sp¹²-Q¹² in which Q¹² is a polymerizable group selectedfrom the group consisting of groups represented by Formulae (Q-1) to(Q-5), as R¹¹.

In addition, in the liquid crystal compound represented by Formula(I-11), R¹¹ is preferably -Z¹¹-Sp¹¹-Q¹¹ in which Z¹¹ is —CO—O—, —O—CO—,—CO—NR¹²—, or NR¹²—CO—, and Q¹¹ is a polymerizable group selected fromthe group consisting of groups represented by Formulae (Q-1) to (Q-5).In addition, in the liquid crystal compound represented by Formula(I-11), R¹¹ is preferably -Z¹²-Sp¹²-Q¹² in which Z¹¹ is —CO—O—,—CO—NR¹²—, or NR¹²—CO—, and Q¹² is a polymerizable group selected fromthe group consisting of groups represented by Formulae (Q-1) to (Q-5).

All 1,4-cyclohexylene groups contained in the liquid crystal compoundrepresented by Formula (I-11) are trans-1,4-cyclohexylene groups.

A suitable aspect of the liquid crystal compound represented by Formula(I-11) may be, for example, a compound in which L¹¹ is a single bond,l¹¹ is 1-(dicyclohexyl group), and Q¹¹ is a polymerizable group selectedfrom the group consisting of groups represented by Formulae (Q-1) to(Q-5).

Another suitable aspect of the liquid crystal compound represented byFormula (I-11) may be, for example, a compound in which m¹¹ is 2, l¹¹ is0, and two R¹¹'s each represent -Z¹¹-Sp¹²-Q¹² , and Q¹² is apolymerizable group selected from the group consisting of groupsrepresented by Formulae (Q-1) to (Q-5).

Liquid crystal compound represented by Formula (I-21)

In the formula, Z²¹ and Z²² each independently represent atrans-1,4-cyclohexylene group which may have a substituent or aphenylene group which may have a substituent,

the above substituents are each independently 1 to 4 substituentsselected from the group consisting of —CO—X²¹-Sp²³-Q²³, an alkyl group,and an alkoxy group,

m21 represents an integer of 1 or 2, and n21 represents an integer of 0or 1,

in a case where m21 represents 2, n21 represents 0,

in a case where m21 represents 2, two Z²¹'s may be the same ordifferent,

at least one of Z²¹ or Z²² is a phenylene group which may have asubstituent,

L²¹, L²², L²³, and L²⁴ each independently represent a single bond or alinking group selected from the group consisting of —CH₂O—, —OCH₂—,—(CH₂)₂—O—CO—, —CO—, —CO—O(CH₂)₂—, —CO—O—, —O—CO—, —O—CO—O—,—CH═CH—CO—O—, and —O—CO—CH═CH—,

X²¹ represents —O—, —S—, or —N(Sp²⁵-Q²⁵)- represents a nitrogen atomforming a ring structure together with Q²³ and Sp²³,

r²¹ represents an integer of 1 to 4,

Sp²¹, Sp²¹, Sp²³, and Sp²⁵ each independently represent a single bond ora linking group selected from the group consisting of a linear orbranched alkylene group having 1 to 20 carbon atoms and a group whereone or two or more —CH₂— in a linear or branched alkylene group having 1to 20 carbon atoms is substituted with —O—, —S—, —NH—, —N(CH₃)—, —CO—,—O—CO—, or —CO—O—,

Q²¹ and Q²² each independently represent a polymerizable group selectedfrom the group consisting of groups represented by Formulae (Q-1) to(Q-5),

Q²³ represents a hydrogen atom, a cycloalkyl group, a group where one ortwo or more —CH₂— in a cycloalkyl group is substituted with —O—, —S—,—NH—, —N(CH₃)—, —CO—, —O—CO—, or —CO—O—, any one polymerizable groupselected from the group consisting of groups represented by Formulae(Q-1) to (Q-5), or a single bond in a case where X²¹ is a nitrogen atomforming a ring structure together with Q²³ and Sp²³, and

Q²⁵ represents a hydrogen atom, a cycloalkyl group, a group where one ortwo or more —CH₂— in a cycloalkyl group is substituted with —O—, —S—,—NH—, —N(CH₃)⇒, —O—CO—, or —CO—O—, or any one polymerizable groupselected from the group consisting of groups represented by Formulae(Q-1) to (Q-5), provided that in a case where Sp²⁵ is a single bond, Q²⁵is not a hydrogen atom.

It is also preferred that the liquid crystal compound represented byFormula (I-21) has a structure in which a 1,4-phenylene group and atrans-1,4-cyclohexylene group are alternately present. For example,preferred is a structure in which m21 is 2, n21 is 0, and Z²¹ is atrans-1,4-cyclohexylene group which may have a substituent or an arylenegroup which may have a substituent, each of which from the Q²¹ side, ora structure in which m21 is 1, n21 is 1, Z²¹ is an arylene group whichmay have a substituent, and Z²² is an arylene group which may have asubstituent.

Liquid crystal compound represented by Formula (I-31);

In the formula, R³¹ and R³² each independently represent an alkyl group,an alkoxy group, and a group selected from the group consisting of—CO—X³¹-Sp³³,

n31 and n32 each independently represent an integer of 0 to 4,

X³¹ represents a single bond, —O—, —S—, or —N(Sp³⁴-Q³⁴)- or represents anitrogen atom forming a ring structure together with Q³³ and Sp³³,

Z³¹ represents a phenylene group which may have a substituent,

Z³² represents a trans-1,4-cyclohexylene group which may have asubstituent or a phenylene group which may have a substituent,

the above substituents are each independently 1 to 4 substituentsselected from the group consisting of an alkyl group, an alkoxy group,and —CO—X³¹-Sp³³-Q³³,

m³¹ represents an integer of 1 or 2, and m32 represents an integer of 0to 2,

in a case where m31 and m32 represent 2, two Z³¹'s and Z³²'s may be thesame or different,

L³¹ and L³² each independently represent a single bond or a linkinggroup selected from the group consisting of —CH₂O—, —OCH₂—, —(CH₂)₂—CO—,—CO—O(CH₂)₂—, —CO—O—, —O—CO—, —O—CO—O—, —CH═CH—CO—O—, and —O—CO—CH═CH—,

Sp³¹, Sp³², Sp³³, and Sp³⁴ each independently represent a single bond ora linking group selected from the group consisting of a linear orbranched alkylene group having 1 to 20 carbon atoms and a group whereone or two or more —CH₂— in a linear or branched alkylene group having 1to 20 carbon atoms is substituted with —O—, —S——NH—, —N(CH₃)—, —CO—,—O—CO—, or —CO—O—,

Q³¹ and Q³² each independently represent a polymerizable group selectedfrom the group consisting of groups represented by Formulae (Q-1) to(Q-5), and

Q³³ and Q³⁴ each independently represent a hydrogen atom, a cycloalkylgroup, a group where one or two or more —CH₂— in a cycloalkyl group issubstituted with —O—, —S—, —NH—, —N(CH₃)—, —CO—, —O—CO—, or —CO—O—, orany one polymerizable group selected from the group consisting of groupsrepresented by Formulae (Q-1) to (Q-5), provided that Q³³ may representa single bond in a case of forming a ring structure together with X³¹and Sp³³, and Q³⁴ is not a hydrogen atom in a case where Sp³⁴ is asingle bond.

As the liquid crystal compound represented by Formula (I-31),particularly preferable compounds include a compound in which Z³² is aphenylene group and a compound in which m32 is 0.

It is also preferred that the compound represented by Formula (I) has apartial structure represented by Formula (II).

In Formula (II), black circles indicate the bonding positions with othermoieties of Formula (I). It is sufficient that the partial structurerepresented by Formula (II) is included as a part of the partialstructure represented by Formula (III) in Formula (I).

In the formula, R¹ and R² are each independently a group selected fromthe group consisting of a hydrogen atom, an alkyl group, an alkoxygroup, and a group represented by —CO—X³-Sp³-Q³. Here, X³ represents asingle bond, —O—, —S—, or —N(Sp⁴-Q⁴)- or represents a nitrogen atomforming a ring structure together with Q³ and Sp³. X³ is preferably asingle bond or —O—. R¹ and R² are preferably —CO—X³-Sp³-Q³. It is alsopreferred that R¹ and R² are the same. The bonding position of each ofR¹ and R² to the phenylene group is not particularly limited.

Sp³ and Sp⁴ each independently represent a single bond or a linkinggroup selected from the group consisting of a linear or branchedalkylene group having 1 to 20 carbon atoms and a group where one or twoor more —CH₂— in a linear or branched alkylene group having 1 to 20carbon atoms are substituted with —O—, —S—, —NH—, —N(CH₃)—, —CO—,—O—CO—, or —CO—O—. Sp³ and Sp⁴ are each independently preferably alinear or branched alkylene group having 1 to 10 carbon atoms, morepreferably a linear alkylene group having 1 to 5 carbon atoms, and stillmore preferably a linear chain alkylene group having 1 to 3 carbonatoms.

Q³ and Q⁴ each independently represent a hydrogen atom, a cycloalkylgroup, a group where one or two or more —CH₂— in a cycloalkyl group aresubstituted with —O—, —S—, —NH—, —N(CH₃)—, —CO—, —O—CO—, or —CO—O—, orany one polymerizable group selected from the group consisting of groupsrepresented by Formulae (Q-1) to (Q-5).

It is also preferred that the compound represented by Formula (I) has,for example, a structure represented by Formula (II-2).

In the formula, A¹ and A² each independently represent a phenylene groupwhich may have a substituent or a trans-1,4-cyclohexylene group whichmay have a substituent, and the above substituents are eachindependently 1 to 4 substituents selected from the group consisting ofan alkyl group, an alkoxy group, and —CO—X³-Sp³-Q³,

L¹, L², and L³ each independently represent a single bond or a linkinggroup selected from the group consisting of —CH₂O—, —OCH₂—,—(CH₂)₂O—CO—, —CO—O(CH₂)₂—, —CO—O—, —O—CO—, —O—CO—O—, —CH═CH—CO—O—, and—O—CO—CH═CH—,

n1 and n2 each independently represent an integer of 0 to 9, and n1+n2is 9 or less.

Each of Q¹, Q², Sp¹, and Sp² has the same definition as that of eachgroup in Formula (I). Each of X³, Sp³, Q³, R¹, and R² has the samedefinition as that of each group in Formula (II).

Another suitable aspect of the liquid crystal compound includes acompound represented by Formula (IV).

Compound represented by Formula (IV)

In Formula (IV), A¹ represents an alkylene group having 2 to 18 carbonatoms, in which one CH₂ or two or more non-adjacent CH₂'s in thealkylene group may be substituted with —O—;

Z¹ represents —CO—,—O—CO—, or a single bond;

Z² represents —CO— or —CO—CH═CH—;

R¹ represents a hydrogen atom or a methyl group;

R² represents a hydrogen atom, a halogen atom, a linear alkyl grouphaving 1 to 4 carbon atoms, a methoxy group, an ethoxy group, a phenylgroup which may have a substituent, a vinyl group, a formyl group, anitro group, a cyano group, an acetyl group, an acetoxy group, anN-acetylamide group, an acryloylamino group, an N,N-dimethylamino group,a maleimide group, a methacryloylamino group, an allyloxy group, anallyloxycarbamoyl group, an N-alkyloxycarbamoyl group in which the alkylgroup has 1 to 4 carbon atoms, an N-(2-methacryloyloxyethyl)carbamoyloxygroup, an N-(2-acryloyloxyethyl)carbamoyloxy group, or a grouprepresented by Formula (IV-2); and

L¹, L², L³, and L⁴ each independently represent an alkyl group having 1to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, analkoxycarbonyl group having 2 to 5 carbon atoms, an acyl group having 2to 4 carbon atoms, a halogen atom, or a hydrogen atom, and at least oneof L¹, L², L³, or L⁴ represents a group other than a hydrogen atom.

-Z⁵-T-Sp-P   Formula (IV-2)

In Formula (IV-2), P represents an acryloyl group, a methacryl group, ora hydrogen atom, and Z⁵ represents a single bond, —CO—O—, —O—CO—,—CO—NR¹— (where R¹ represents a hydrogen atom or a methyl group),—NR¹—CO—, —CO—S—, or —S—CO—, T represents 1,4-phenylene, and Sprepresents a divalent aliphatic group having 1 to 12 carbon atoms whichmay have a substituent, in which one CH2 or two or more non-adjacentCH2's in the aliphatic group may be substituted with —O—, —S—, —O—CO—,—CO—O—, or —O—CO—O—.

The compound represented by Formula (IV) is preferably a compoundrepresented by Formula (V).

Compound represented by Formula (V)

In Formula (V), n1 represents an integer of 3 to 6;

R¹¹ represents a hydrogen atom or a methyl group;

R¹² represents —CO— or —CO—CH═CH—; and

R¹² represents a hydrogen atom, a linear alkyl group having 1 to 4carbon atoms, a methoxy group, an ethoxy group, a phenyl group, anacryloylamino group, a methacryloylamino group, an allyloxy group, or agroup represented by Formula (IV-3).

-Z⁵¹-T-Sp-P   Formula (IV-3)

In Formula (IV-3), P represents an acryloyl group or a methacryl group;

Z⁵¹ represents —CO—O— or —O—CO—;

T represents 1,4-phenylene; and

Sp represents a divalent aliphatic group having 2 to 6 carbon atomswhich may have a substituent, in which one CH₂ or two or morenon-adjacent CH₂'s in the aliphatic group may be substituted with —O—,—O—CO—, —CO—O—, or O(═O)OO—.

n1 represents an integer of 3 to 6 and is preferably 3 or 4.

Z¹² represents —CO— or CO—CH═CH— and preferably represents —CO—.

R¹² represents a hydrogen atom, a linear alkyl group having 1 to 4carbon atoms, a methoxy group, an ethoxy group, a phenyl group, anacryloylamino group, a methacryloylamino group, an allyloxy group, or agroup represented by Formula (IV-3), more preferably represents a methylgroup, an ethyl group, a propyl group, a methoxy group, an ethoxy group,a phenyl group, an acryloylamino group, a methacryloylamino group, or agroup represented by Formula (IV-3), and still more preferablyrepresents a methyl group, an ethyl group, a methoxy group, an ethoxygroup, a phenyl group, an acryloylamino group, a methacryloylaminogroup, or a group represented by Formula (IV-3).

Note that R is intended to refer to Me.

Specific examples of the compound represented by Formula (IV) includethe compounds exemplified below.

Another suitable aspect of the liquid crystal compound includes acompound represented by Formula (VI).

Compound represented by Formula (VI)

In Formula (VI), Z³ represents —CO— or —CH═CH—CO—;

Z⁴ represents —CO— or —CO—CH═CH—;

R³ and R⁴ each independently represent a hydrogen atom, a halogen atom,a linear alkyl group having 1 to 4 carbon atoms, a methoxy group, anethoxy group, an aromatic group which may have a substituent, acyclohexyl group, a vinyl group, a formyl group, a nitro group, a cyanogroup, an acetyl group, an acetoxy group, an acryloylamino group, anN,N-dimethylamino group, a maleimide group, a methacryloylamino group,an allyloxy group, an allyloxycarbamoyl group, an N-alkyloxycarbamoylgroup in which the alkyl group has 1 to carbon atoms, anN-(2-methacryloyloxyethyl)carbamoyloxy group, anN-(2-acryloyloxyethyl)carbamoyloxy group, or a group represented byFormula (VI-2); and

L⁵, L⁶, L⁷, and L⁸ each independently represent an alkyl group having 1to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, analkoxycarbonyl group having 2 to 5 carbon atoms, an acyl group having 2to 4 carbon atoms, a halogen atom, or a hydrogen atom, and at least oneof L⁵, L⁶, L⁷,or L⁸ represents a group other than a hydrogen atom.

-Z⁵-T-Sp-P   Formula (VI-2)

In Formula (VI-2), P represents an acryloyl group, a methacryl group, ora hydrogen atom, and Z⁵ represents CO—O—, —O—CO—, —CO—NR¹— (where R¹represents a hydrogen atom or a methyl group), —NR¹—CO—, —CO—S—, orS—CO—, T represents 1,4-phenylene, and Sp represents a divalentaliphatic group having 1 to 12 carbon atoms which may have asubstituent, in which one CH₂ or two or more non-adjacent CH₂'s in thealiphatic group may be substituted with —O—, —S—, —O—CO—, —CO—O—, or—O—CO—O—.

The compound represented by Formula (VI) is preferably a compoundrepresented by Formula (VII).

Compound represented by Formula (VII)

In Formula (VII), Z¹³ represents —CO— or —CO—CH═CH—;

Z¹⁴ represents —CO— or —CH═CH—CO—; and

R¹³ and R¹⁴ each independently represent a hydrogen atom, a linear alkylgroup having 1 to 4 carbon atoms, a methoxy group, an ethoxy group, aphenyl group, an acryloylamino group, a methacryloylamino group, anallyloxy group, or a group represented by Formula (IV-3).

Z¹³ represents —CO— or —CO—CH═CH— and preferably represents —CO—.

R¹³ and R¹⁴ each independently represent a hydrogen atom, a linear alkylgroup having 1 to 4 carbon atoms, a methoxy group, an ethoxy group, aphenyl group, an acryloylamino group, a methacryloylamino group, anallyloxy group, or a group represented by Formula (IV-3), preferablyrepresents a methyl group, an ethyl group, a propyl group, a methoxygroup, an ethoxy group, a phenyl group, an acryloylamino group, amethacryloylamino group, or a group represented by Formula (IV-3), andmore preferably represents a methyl group, an ethyl group, a methoxygroup, an ethoxy group, a phenyl group, an acryloylamino group, amethacryloylamino group, or a group represented by Formula (IV-3).

Specific examples of the compound represented by Formula (VI) includethe compounds exemplified below.

Another suitable aspect of the liquid crystal compound includes acompound represented by Formula (VIII).

Compound represented by Formula (VIII)

In Formula (VIII), A² and A³ each independently represent an alkylenegroup having 2 to 18 carbon atoms, and one CH₂ or two or morenon-adjacent CH₂'s in the alkylene group may be substituted with —O—;

Z⁵ represents —CO—, —O—CO—, or a single bond;

Z⁶ represents —CO—, —CO—O—, or a single bond;

R⁵ and R⁶ each independently represent a hydrogen atom or a methylgroup; and

L⁹, L¹⁰, ¹¹, and L¹² each independently represent an alkyl group having1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, analkoxycarbonyl group having 2 to 5 carbon atoms, an acyl group having 2to 4 carbon atoms, a halogen atom, or a hydrogen atom, and at least oneof L⁹, L¹⁰, L¹¹, or L¹², or L¹² represents a group other than a hydrogenatom.

The compound represented by Formula (VIII) is preferably a compoundrepresented by Formula (IX).

Compound represented by Formula (IX)

In Formula (IX), n2 and n3 each independently represent an integer of 3to 6; and

R¹⁵ and R¹⁶ each independently represent a hydrogen atom or a methylgroup.

In Formula (IX), it is preferred that n2 and n3 each independentlyrepresent an integer of 3 to 6, and n2 and n3 are 4.

In Formula (IX), it is preferred that R¹⁵ and R¹⁶ each independentlyrepresent a hydrogen atom or a methyl group, and R¹⁵ and R¹⁶ eachrepresent a hydrogen atom.

Specific examples of the compound represented by Formula (VIII) includethe compounds exemplified below.

The liquid crystal compound can be produced by a known method.

The content of the liquid crystal compound in the liquid crystalcomposition is preferably 50% by mass or more, more preferably 60% bymass or more, and still more preferably 60% to 95% by mass with respectto the total solid content of the composition.

Chiral Agent

The liquid crystal composition may contain a chiral agent.

The type of chiral agent (chiral compound) is not particularly limited.The chiral agent may be liquid crystalline or non-liquid crystalline.The chiral agent may be selected from a variety of known chiral agents(for example, as described in Liquid Crystal Device Handbook, Chap. 3,Item 4-3, Chiral Agents for Twisted Nematic (TN) and Super TwistedNematic (STN), p. 199, edited by the 142^(nd) Committee of the JapanSociety for the Promotion of Science, 1989). The chiral agent generallycontains an asymmetric carbon atom. However, an axial asymmetriccompound or planar asymmetric compound not containing an asymmetriccarbon atom may also be used as the chiral agent. Examples of the axialasymmetric compound or the planar asymmetric compound includebinaphthyl, helicene, paracyclophane, and derivatives thereof. Thechiral agent may have a polymerizable group.

The content of the chiral agent in the composition is preferably 0.5% to30% by mass with respect to the total mass of the liquid crystalcompound. The chiral agent is preferably used in a smaller amount, as ittends not to affect the liquid crystallinity. Accordingly, the chiralagent is preferably a compound having a strong twisting power in orderthat the compound could achieve twisted alignment of a desired helicalpitch even in a case where the amount thereof used is small.

Examples of such a chiral agent having strong twisting power include thechiral agents described in, for example, JP2002-302487A, JP2002-080478A,JP2002-080851A, JP2002-179668A, JP2002-179670A, JP2002-338575A,JP2002-180051A, JP1987-081354A (JP-S62-081354A), WO2002/006195A,JP2011-241215A, JP2003-287623A, and JP2014-034581A, and LC-756manufactured by BASF SE.

Optional Components

The liquid crystal composition may contain components other than theliquid crystal compound and the specific copolymer.

<Polymerization Initiator>

The liquid crystal composition may contain a polymerization initiator.

The polymerization initiator is preferably a photopolymerizationinitiator capable of initiating a polymerization reaction uponirradiation with ultraviolet rays. Examples of the photopolymerizationinitiator include a-carbonyl compounds (as described in U.S. Pat. Nos.2,367,661A and 2,367,670A), acyloin ethers (as described in U.S. Pat.No. 2,448,828A), α-hydrocarbon-substituted aromatic acyloin compounds(as described in U.S. Pat. No. 2,722,512A), polynuclear quinonecompounds (as described in U.S. Pat. Nos. 3,046,127A and 2,951,758A),combinations of triarylimidazole dimer and p-aminophenyl ketone (asdescribed in U.S. Pat. No. 3,549,367A), acridine and phenazine compounds(as described in JP1985-105667A (JP-S60-105667A) and U.S. Pat. No.4,2398,50A), and oxadiazole compounds (as described in U.S. Pat. No.4,212,970A).

The content of the polymerization initiator in the liquid crystalcomposition is not particularly limited, but it is preferably 0.1% to20% by mass and more preferably 1% to 10% by mass, with respect to thetotal solid content of the liquid crystal compound.

<Other Additives>

The liquid crystal composition may contain one or two or more otheradditives such as an antioxidant, an ultraviolet absorber, a sensitizer,a stabilizer, a plasticizer, a chain transfer agent, a polymerizationinhibitor, an antifoaming agent, a leveling agent, a thickener, a flameretardant, a surface-active substance, a dispersant, and a colormaterial such as a dye and a pigment.

The liquid crystal composition may contain a thickener for the purposeof increasing the viscosity.

The thickener is preferably one capable of increasing the viscositywithout significantly disturbing the alignment of the liquid crystal.For example, a polymer having a mesogenic structure is preferable.

Further, for example, a compound having a hydrogen bonding functionalgroup is also preferable. The hydrogen bonding functional group ispreferably a hydroxyl group, an amino group, a carboxyl group, a sulfogroup, an amido group, a urethane group, a urea group, or the like.

Reflective Layer

The liquid crystal composition can be applied to various applications.Specifically, a cured product (for example, in the form of a film or thelike) is obtained by subjecting the liquid crystal composition to apolymerization treatment (light irradiation treatment, heat treatment,or the like), and the cured product can be suitably applied, forexample, as an optically anisotropic body and a reflective layer havingexcellent diffuse reflectivity. In addition, the optically anisotropicbody is intended to refer to a substance which has optical anisotropy.In addition, the reflective layer corresponds to a layer formed byfixing a cholesteric liquid crystalline phase and can reflect light in apredetermined reflection band.

Method for Producing Reflective Layer

Hereinafter, a method for producing a reflective layer according to theembodiment of the present invention will be described.

The method for producing a reflective layer according to the embodimentof the present invention preferably has the following steps 1 to 3.

Step 1: a step of forming a composition layer using the above-mentionedliquid crystal composition on a transparent base material that has notbeen subjected to a uniaxial alignment treatment

Step 2: a step in which the liquid crystal compound contained in thecomposition layer obtained through the step 1 is aligned into acholesteric liquid crystalline phase state.

Step 3: a step of fixing the cholesteric liquid crystalline phase afterthe step 2

Step 1

In the step 1, first, the above-mentioned composition layer is prepared.

The method for producing the composition layer is not particularlylimited and may be, for example, a method in which the liquid crystalcomposition is applied onto a base material to form a composition layer.

The base material is not particularly limited as long as it is notsubjected to a uniaxial alignment treatment and supports the compositionlayer. With regard to the base material, more random alignment of thesurface on which the composition layer is formed leads to more excellentdiffuse reflectivity of a reflective layer to be formed.

The base material is particularly preferably a transparent basematerial. The transparent base material is intended to refer to a basematerial having a transmittance of visible light of 60% or more, and thetransmittance thereof is preferably 80% or more and more preferably 90%or more. Note that the upper limit value of the transmittance is 100% orless.

The material constituting the base material is not particularly limited,and examples thereof include a cellulose-based polymer, apolycarbonate-based polymer, a polyester-based polymer, a (meth)acrylicpolymer, a styrene-based polymer, a polyolefin-based polymer, a vinylchloride-based polymer, an amide-based polymer, an imide-based polymer,a sulfone-based polymer, a polyether sulfone-based polymer, and apolyether ether ketone-based polymer. The base material is preferably apolymer obtained by curing a mixture of pentaerythritol triacrylate andpentaerythritol tetraacrylate, from the viewpoint that the diffusereflectivity of the reflective layer is more excellent.

The base material may have a single-layer structure or a multilayerstructure. In a case where the base material has a multilayer structure,the layer on the reflective layer side may be a layer that has not beensubjected to a uniaxial alignment treatment.

The base material may contain various additives such as an ultraviolet(UV) absorber, a matting agent fine particle, a plasticizer, adeterioration inhibitor, and a release agent.

In addition, the base material preferably has low birefringence in thevisible light region. For example, the phase difference at a wavelengthof 550 nm of the base material is preferably 50 nm or less and morepreferably 20 nm or less.

The thickness of the base material is not particularly limited, but itis preferably 10 to 200 μm and more preferably 20 to 100 μm from theviewpoint of thinning and handleability.

The thickness is intended to refer to an average thickness, and isobtained by measuring thicknesses at any five places of the basematerial and arithmetically averaging the measured values.

In a case where the above-mentioned composition is applied, thecomposition may contain a solvent, if necessary.

The solvent may be, for example, water or an organic solvent. Examplesof the organic solvent include amides such as N,N-dimethylformamide;sulfoxides such as dimethylsulfoxide; heterocyclic compounds such aspyridine; hydrocarbons such as benzene and hexane; alkyl halides such aschloroform and dichloromethane; esters such as methyl acetate, butylacetate, and propylene glycol monoethyl ether acetate; ketones such asacetone, 2-butanone, methyl ethyl ketone, cyclohexanone, andcyclopentanone; ethers such as tetrahydrofuran and 1,2-dimethoxyethane;and 1,4-butanediol diacetate. These solvents may be used alone or incombination of two or more thereof.

The method of applying the composition onto the base material is notparticularly limited, and examples thereof include a wire bar coatingmethod, an extrusion coating method, a direct gravure coating method, areverse gravure coating method, and a die-coating method.

If necessary, a treatment for drying the composition applied onto thebase material may be carried out after application. By carrying out thedrying treatment, the solvent can be removed from the appliedcomposition.

The film thickness of the composition layer disposed on the basematerial is not particularly limited, but is preferably 0.1 to 20 μm,more preferably 0.2 to 15 μm, and still more preferably 0.5 to 10 μmfrom the viewpoint of more excellent diffuse reflectivity of thereflective layer.

Step 2

The step 2 is a step in which the liquid crystal compound contained inthe composition layer obtained through the step 1 is aligned into acholesteric liquid crystalline phase state.

The method of aligning the liquid crystal compound may be, for example,a method of heating the composition layer. Specifically, the composition(composition layer) applied onto the substrate is heated to align theliquid crystal compound in the composition layer into a cholestericliquid crystalline phase state.

The liquid crystalline phase transition temperature of the compositionlayer is preferably in the range of 10° C. to 250° C. and morepreferably in the range of 10° C. to 150° C., from the viewpoint ofmanufacturing suitability.

As to preferred heating conditions, it is preferable to heat thecomposition layer at 40° C. to 100° C. (preferably 60° C. to 100° C.)for 0.5 to 5 minutes (preferably 0.5 to 2 minutes).

In a case of heating the composition layer, it is preferable not to heatthe composition layer to a temperature at which the liquid crystalcompound becomes an isotropic phase (Iso). In a case where thecomposition layer is heated above the temperature at which the liquidcrystal compound becomes an isotropic phase, defects of the cholestericliquid crystalline phase are increased, which is not preferable.

Step 3

The step 3 corresponds to a step of fixing the cholesteric liquidcrystalline phase, and is carried out after the step 2. That is, thereflective layer obtained through the step 3 corresponds to a layerformed by fixing the cholesteric liquid crystalline phase.

Here, as the state where the cholesteric liquid crystalline phase is“fixed”, the most typical and preferred aspect is a state in which thealignment of the liquid crystal compound brought into a cholestericliquid crystalline phase is retained. The state where the liquidcrystalline phase is “fixed” is not limited thereto, and specifically,it refers to a state in which, in a temperature range of usually 0° C.to 50° C. and in a temperature range of −30° C. to 70° C. under moresevere conditions, the layer has no fluidity and can keep an fixedalignment state stably without causing changes in alignment state due toexternal field or external force. In the present invention, as will bedescribed later, it is preferable to fix the alignment state of acholesteric liquid crystalline phase by a curing reaction proceedingupon irradiation with ultraviolet rays.

In the layer obtained by fixing a cholesteric liquid crystalline phase,it is sufficient that the optical properties of the cholesteric liquidcrystalline phase are retained in the layer, and finally the compositionin the layer no longer needs to show liquid crystallinity.

The method of the fixing treatment is not particularly limited, andexamples thereof include a photo curing treatment and a thermal curingtreatment. Among them, a light irradiation treatment is preferable, andan ultraviolet irradiation treatment is more preferable. Such a fixingtreatment is preferably a polymerization reaction upon light irradiation(particularly ultraviolet irradiation), and more preferably a radicalpolymerization reaction upon light irradiation (particularly ultravioletirradiation).

For ultraviolet irradiation, a light source such as an ultraviolet lampis used.

The irradiation energy quantity of ultraviolet rays is not particularlylimited, but it is generally preferably about 0.1 to 0.8 J/cm². Theirradiation time of the ultraviolet rays is not particularly limited,but it may be determined as appropriate from the viewpoint of bothsufficient strength and productivity of the obtained reflective layer.

Step 4

The method for producing a reflective layer according to the embodimentof the present invention preferably includes a step 4, which is a stepof cooling the composition layer in a cholesteric liquid crystallinephase state, between the step 2 and the step 3, from the viewpoint offurther improving the diffuse reflectivity of the reflective layer. Inparticular, in a case where the liquid crystal composition contains achiral agent whose helical twisting power (HTP) changes depending on thetemperature, a reflective layer having more excellent diffusereflectivity can be formed through the step 4.

In a case where the composition is cooled, it is preferable to cool thecomposition layer such that the temperature of the composition layer islowered by 30° C. or more, from the viewpoint that the diffusereflectivity of the reflective layer is more excellent. Above all, fromthe viewpoint that the above effect is more excellent, it is preferableto cool the composition layer so as to lower by 40° C. or more, and itis more preferable to cool the composition layer so as to lower by 50°C. or more. The upper limit value of the reduced temperature range ofthe cooling treatment is not particularly limited, but is usually about70° C.

In other words, the above cooling treatment is intended to cool thecomposition layer so as to be T-30° C. or less in a case where thetemperature of the composition layer in a cholesteric liquid crystallinephase state before cooling is T ° C.

The cooling method is not particularly limited, and includes a method inwhich a substrate on which the composition layer is disposed is allowedto stand in an atmosphere at a predetermined temperature.

In a case where the step 4 is carried out, it is preferable that theabove-described fixing treatment in the step 3 is carried outsimultaneously with the step 4 or after the step 4.

Applications of Reflective Layer

The reflective layer is a layer showing selective reflection propertieswith respect to light in a predetermined wavelength range. Thereflective layer functions as a circularly polarized selectivereflective layer that selectively reflects either the dextrorotatorycircularly polarized light or the levorotatory circularly polarizedlight in the selective reflection wavelength range and transmits theother sense circularly polarized light. A film including one or two ormore reflective layers can be used for various applications. In a filmincluding two or more layers of a reflective layer, the senses ofcircularly polarized light reflected by the reflective layers may be thesame or opposite to each other depending on the application. Inaddition, the center wavelengths of selective reflection of thereflective layers, which will be described later, may be the same as ordifferent from each other depending on the application.

In the present specification, the term “sense” for circularly polarizedlight means dextrorotatory circularly polarized light or levorotatorycircularly polarized light. The sense of circularly polarized light isdefined such that, in a case where light is viewed as it proceeds towardan observer and in a case where the distal end of the electric fieldvector rotates clockwise as time increases, the sense is dextrorotatorycircularly polarized light, and in a case where it rotatescounterclockwise, the sense is levorotatory circularly polarized light.In the present specification, the term “sense” may be used for thetwisted direction of the helix of the cholesteric liquid crystal.Selective reflection by the cholesteric liquid crystal reflectsdextrorotatory circularly polarized light and transmits levorotatorycircularly polarized light in a case where the twisted direction (sense)of the helix of the cholesteric liquid crystal is right-handed, whereasit reflects levorotatory circularly polarized light and transmitsdextrorotatory circularly polarized light in a case where the sense isleft-handed.

For example, a film including a reflective layer exhibiting selectivereflection properties in the visible light wavelength range (wavelengthof 400 to 750 nm) can be used as a screen for projected image displayand a half mirror. Further, by controlling the reflection band, such afilm can be used as a filter that improves the color purity of displaylight of a color filter or a display (for example, see JP2003-294948A).

In addition, the reflective layer can be used for various applicationssuch as a polarizing element, a reflective film, an anti-reflectionfilm, a viewing angle compensating film, holography, and an alignmentfilm, which are constituent elements of an optical element.

Hereinafter, the application as a projected image display member whichis a particularly preferable application will be described.

By the above-mentioned function of the reflective layer, a projectedimage can be formed by reflecting circularly polarized light of eithersense at the wavelength showing selective reflection among the projectedlight. The projected image may be visually recognized as such by beingdisplayed on the surface of the projected image display member or may bea virtual image which appears to float above the projected image displaymember as viewed from an observer.

The center wavelength λ of the selective reflection depends on the pitchP of the helical structure (=the period of the helix) in a cholestericliquid crystalline phase and follows the relationship of λ=n×P with theaverage refractive index n of the reflective layer. Here, the centerwavelength λ of the selective reflection of the reflective layer means awavelength at the center position of the reflection peak of thecircularly polarized reflection spectrum measured from the normaldirection of the reflective layer. As can be seen from the aboveExpression, the center wavelength of the selective reflection can beadjusted by adjusting the pitch of the helical structure. That is, byadjusting the n value and the P value, for example, in order toselectively reflect either the dextrorotatory circularly polarized lightor the levorotatory circularly polarized light with respect to the bluelight, the center wavelength X, is adjusted so that an apparent centerwavelength of the selective reflection can be set to a wavelength rangeof 450 to 495 nm. Incidentally, the apparent center wavelength of theselective reflection means a wavelength at the center position of thereflection peak of the circularly polarized reflection spectrum of thereflective layer measured from the observation direction in practicaluse (in a case of being used as a projected image display member). Sincethe pitch of the cholesteric liquid crystalline phase depends on thetype of the chiral agent to be used together with the liquid crystalcompound or the addition concentration thereof, a desired pitch can beobtained by adjusting these factors. For the method of measuring thesense and pitch of helix, methods described in “Easy Steps in LiquidCrystal Chemistry Experiment” p 46, edited by The Japanese LiquidCrystal Society, Sigma Publishing, published in 2007, and “LiquidCrystal Handbook” p 196, Editorial Committee of Liquid Crystal Handbook,Maruzen can be used.

In addition, a projected image display member capable of displaying fullcolor projected images can be produced by preparing and laminatingreflective layers having an apparent center wavelength of the selectivereflection in the red light wavelength range, the green light wavelengthrange, and the blue light wavelength range, respectively.

By adjusting the center wavelength of the selective reflection of eachreflective layer according to the emission wavelength range of the lightsource used for projection and the mode of use of the projected imagedisplay member, a clear projected image can be displayed with highefficiency of light utilization. In particular, by adjusting the centerwavelengths of the selective reflection of the reflective layerrespectively according to the light emission wavelength range of thelight source used for projection or the like, a clear color projectedimage can be displayed with high efficiency of light utilization.

In addition, for example, in a case where the projected image displaymember is configured to be transmissive to light in the visible lightregion, a half mirror that can be used as a combiner for a head-updisplay can be obtained. The projected image display half mirror candisplay the image projected from the projector in a visible manner, andin a case where the projected image display half mirror is observed fromthe same surface side where the image is displayed, can simultaneouslyobserve the information or scenery on the opposite surface side.

Copolymer

The copolymer according to the embodiment of the present inventioncontains a repeating unit derived from the monomer represented byGeneral Formula (X2) and a repeating unit derived from the monomerrepresented by General Formula (Y1), and has a weight-average molecularweight of less than 10,000. That is, the copolymer according to theembodiment of the present invention corresponds to one embodiment of thespecific copolymer described above. The suitable aspect of the copolymeris the same as the suitable aspect of the specific copolymer describedabove, and therefore the description thereof will be omitted.

EXAMPLES

Hereinafter, the present invention will be described in more detail withreference to Examples. The materials, the used amount, the ratio, thecontents of a treatment, and the procedures of a treatment described inExamples below may be suitably modified without departing from thespirit of the present invention. Accordingly, the scope of the presentinvention should not be limitatively interpreted by Examples describedbelow.

Synthesis Example of Copolymer

Hereinafter, Synthesis Examples of copolymer 1-1 and copolymer 1-8 usedin the Examples are shown as examples.

Synthesis Example 1: Synthesis of Copolymer 1-1 Synthesis Example ofMonomer 1

According to JP2013-067603A, monomer 1 was synthesized according to thefollowing synthesis procedure. In addition, “MSCI” is intended to referto methanesulfonyl chloride, and “TEA” is intended to refer totriethylamine.

Synthesis Example of Copolymer 1-1

84 g of cyclohexanone was charged into a 500 ml three-neck flaskequipped with a stirrer, a thermometer, a reflux cooling pipe, and anitrogen gas inlet, the inside of the flask was sufficiently purged withnitrogen, and then the temperature was raised to an internal temperatureof 80° C.

Then, a mixed solution of 13.8 g (32.9 mmol) of 2-(perfluorohexyl)ethylacrylate, 23.8 g (48.6 mmol) of monomer 1, 209 g of cyclohexanone, and0.68 g of an azo polymerization initiator (V-601, manufactured by WakoPure Chemical Industries, Ltd.) was added dropwise into the flask at aconstant speed such that the dropwise addition was completed in 180minutes. After the completion of the dropwise addition, the obtainedreaction solution was further stirred at 80° C. for 2 hours, and then0.07 g of an azo polymerization initiator (V-601, manufactured by WakoPure Chemical Industries, Ltd.) was added thereto. Thereafter, thetemperature of the reaction solution was raised to 90° C., and stirringwas further continued for 2 hours to obtain copolymer 1-1 represented bythe following formula.

The weight-average molecular weight (Mw) of the copolymer 1-1 was 5,800(calculated in terms of polystyrene by gel permeation chromatography(GPC), in which the columns used were TSKgel SuperHZM-H, TSKgelSuperHZ4000, and TSKgel SuperHZ200 (manufactured by Tosoh Corporation)).

The compositional ratio of each repeating unit in the copolymer 1-1 isbased on “% by mass”. The compositional ratio of each repeating unit inthe copolymer 1-2 to copolymer 1-10 and alignment control agent X-1 toalignment control agent X-4 is also based on “% by mass”.

Synthesis Example 2: Synthesis of Copolymer 1-8 Synthesis Example ofMonomer 2

According to Synthesis Example of monomer 1, monomer 2 was synthesizedaccording to the following synthesis procedure.

Synthesis Example of Copolymer 1-8>

8.5 g (20.3 mmol) of 2-(perfluorohexyl)ethyl acrylate, 19.7 g (33.7mmol) of monomer 2, and 135 g of cyclohexanone were charged into a 300ml three-neck flask equipped with a stirrer, a thermometer, a refluxcooling pipe, and a nitrogen gas inlet, the inside of the flask wassufficiently purged with nitrogen, and then the temperature was raisedto an internal temperature of 80° C.

Next, a mixed solution of 1.0 g of an azo polymerization initiator(V-601, manufactured by Wako Pure Chemical Industries, Ltd.) and 31.3 gof cyclohexanone was added dropwise into the flask at a constant speedsuch that the dropwise addition was completed in 210 minutes. After thecompletion of the dropwise addition, the obtained reaction solution wasstirred at 80° C. for 2 hours, then heated to 90° C., and furtherstirred for 2 hours to obtain copolymer 1-8 represented by the followingformula.

The weight-average molecular weight (Mw) of the copolymer 1-8 was 8,800(calculated in terms of polystyrene by gel permeation chromatography(GPC), in which the columns used were TSKgel SuperHZM-H, TSKgelSuperHZ4000, and TSKgel SuperHZ200 (manufactured by Tosoh Corporation)).

Preparation of Liquid Crystal Composition

The components shown in Table 1 below were mixed to prepare liquidcrystal compositions of Examples 1 to 12 (corresponding to liquidcrystal compositions 1 to 12) and liquid crystal compositions 1 to 5 ofComparative Examples (corresponding to liquid crystal compositions 13 to17). Table 1 is shown below.

TABLE 1 Composition of liquid crystal composition Chiral agentPolymerizable liquid crystal compound Chiral agent Type of Rod-likeRod-like Rod-like LC-756 liquid crystal liquid crystal liquid crystalliquid crystal (manufactured Chiral composition compound 201 compound202 compound 203 by BASF SE) agent A Example 1 Liquid crystal 84 parts14 parts 2 parts 4.9 parts — composition 1 by mass by mass by mass bymass Example 2 Liquid crystal 84 parts 14 parts 2 parts — 4.5 partscomposition 2 by mass by mass by mass by mass Example 3 Liquid crystal84 parts 14 parts 2 parts 4.9 parts — composition 3 by mass by mass bymass by mass Example 4 Liquid crystal 84 parts 14 parts 2 parts — 4.5parts composition 4 by mass by mass by mass by mass Example 5 Liquidcrystal 84 parts 14 parts 2 parts 4.9 parts — composition 5 by mass bymass by mass by mass Example 6 Liquid crystal 84 parts 14 parts 2 parts4.9 parts — composition 6 by mass by mass by mass by mass Example 7Liquid crystal 84 parts 14 parts 2 parts 4.9 parts — composition 7 bymass by mass by mass by mass Example 8 Liquid crystal 84 parts 14 parts2 parts 4.9 parts — composition 8 by mass by mass by mass by massComposition of liquid crystal composition Polymerization initiatorSolvent Polymerization Cyclohexanone 2-butanone initiator (manufactured(manufactured IRG OXE-01 Alignment by Wako Pure by Wako Pure(manufactured control agent Chemical Chemical by BASF SE) Type ContentIndustries, Ltd.) Industries, Ltd.) Example 1 2 parts Copolymer 1-1 0.15parts 25 parts 200 parts by mass by mass by mass by mass Example 2 2parts Copolymer 1-1 0.15 parts 25 parts 200 parts by mass by mass bymass by mass Example 3 2 parts Copolymer 1-2 0.15 parts 25 parts 200parts by mass by mass by mass by mass Example 4 2 parts Copolymer 1-20.15 parts 25 parts 200 parts by mass by mass by mass by mass Example 52 parts Copolymer 1-3 0.15 parts 25 parts 200 parts by mass by mass bymass by mass Example 6 2 parts Copolymer 1-4 0.15 parts 25 parts 200parts by mass by mass by mass by mass Example 7 2 parts Copolymer 1-50.15 parts 25 parts 200 parts by mass by mass by mass by mass Example 82 parts Copolymer 1-6 0.15 parts 25 parts 200 parts by mass by mass bymass by mass Composition of liquid crystal composition Polymerizationinitiator Chiral agent Polymerization Polymerizable liquid crystalcompound Chiral agent initiator Type of Rod-like Rod-like Rod-likeLC-756 IRG OXE-01 liquid crystal liquid crystal liquid crystal liquidcrystal (manufactured (manufactured composition compound 201 compound202 compound 203 by BASF SE) by BASF SE) Example 9 Liquid crystal 84parts 14 parts 2 parts 4.9 parts 2 parts composition 9 by mass by massby mass by mass by mass Example 10 Liquid crystal 84 parts 14 parts 2parts 4.9 parts 2 parts composition 10 by mass by mass by mass by massby mass Example 11 Liquid crystal 84 parts 14 parts 2 parts 4.9 parts 2parts composition 11 by mass by mass by mass by mass by mass Example 12Liquid crystal 84 parts 14 parts 2 parts 4.9 parts 2 parts composition12 by mass by mass by mass by mass by mass Comparative Liquid crystal 84parts 14 parts 2 parts 4.9 parts 2 parts Example 1 composition 13 bymass by mass by mass by mass by mass Comparative Liquid crystal 84 parts14 parts 2 parts 4.9 parts 2 parts Example 2 composition 14 by mass bymass by mass by mass by mass Comparative Liquid crystal 84 parts 14parts 2 parts 4.9 parts 2 parts Example 3 composition 15 by mass by massby mass by mass by mass Comparative Liquid crystal 84 parts 14 parts 2parts 4.9 parts 2 parts Example 4 composition 16 by mass by mass by massby mass by mass Comparative Liquid crystal 84 parts 14 parts 2 parts 4.9parts 2 parts Example 5 composition 17 by mass by mass by mass by massby mass Composition of liquid crystal composition Solvent Cyclohexanone2-butanone (manufactured by (manufactured by Alignment control agentWako Pure Chemical Wako Pure Chemical Type Content Industries, Ltd.)Industries, Ltd.) Example 9 Copolymer 1-7 0.15 parts 25 parts 200 partsby mass by mass by mass Example 10 Copolymer 1-8 0.15 parts 25 parts 200parts by mass by mass by mass Example 11 Copolymer 1-9 0.15 parts 25parts 200 parts by mass by mass by mass Example 12 Copolymer 1-10 0.15parts 25 parts 200 parts by mass by mass by mass Comparative — — 25parts 200 parts Example 1 by mass by mass Comparative Copolymer X-1 0.15parts 25 parts 200 parts Example 2 by mass by mass by mass ComparativeCopolymer X-2 0.15 parts 25 parts 200 parts Example 3 by mass by mass bymass Comparative Copolymer X-3 0.15 parts 25 parts 200 parts Example 4by mass by mass by mass Comparative Copolymer X-4 0.15 parts 25 parts200 parts Example 5 by mass by mass by mass

The various components shown in Table 1 are shown below.

Copolymer 1-1 to Copolymer 1-10

The copolymer 1-1 to copolymer 1-10 shown in Table 1 are shown below.

Rod-Like Liquid Crystal Compound 201

The rod-like liquid crystal compound 201 shown in Table 1 is shownbelow.

Rod-Like Liquid Crystal Compound 202

The rod-like liquid crystal compound 202 shown in Table 1 is shownbelow.

Rod-Like Liquid Crystal Compound 203

The rod-like liquid crystal compound 203 shown in Table 1 is shownbelow.

Chiral Agent A

The chiral agent A shown in Table 1 is shown below.

Note that the chiral agent A is a chiral agent whose helical twistingpower (HTP) changes depending on the temperature, and in a case ofcomparing the absolute value of HTP at 95° C. with the absolute value ofHTP at 30° C., the absolute value of HTP at 30° C. is larger.

Alignment Control Agent X-1

The alignment control agent X-1 shown in Table 1 is shown below. Acompound synthesized according to JP2006-016599A was used as thealignment control agent X-1.

Alignment Control Agent X-2

The alignment control agent X-2 shown in Table 1 is shown below.

Alignment Control Agent X-3

The alignment control agent X-3 shown in Table 1 is shown below.

Alignment Control Agent X-4

The alignment control agent X-4 shown in Table 1 is shown below. Acompound synthesized according to JP2007-217656A was used as thealignment control agent X-4.

Preparation of Base Material Preparation of Polymerizable CompositionCoating Liquid A

The following components were mixed to prepare a polymerizablecomposition coating liquid A.

PET30 100 parts by mass (manufactured by Nippon Kayaku Co., Ltd.)Polymerization initiator 3 parts by mass (Irg819, manufactured by BASFSE) MEK 200 parts by mass (methyl ethyl ketone, manufactured by WakoPure Chemical Industries, Ltd.)

Preparation of Acrylic Layer A

The polymerizable composition coating liquid A was applied onto a PET(polyethylene terephthalate) film (manufactured by Toyobo Co., Ltd.) atroom temperature using a wire bar. The obtained coating layer was driedat room temperature for 30 seconds, and then heated in an atmosphere at85° C. for 2 minutes.

Thereafter, the coating film was irradiated with ultraviolet rays at 30°C. for 6 seconds using a D bulb (lamp 90 mW/cm², output 60%,manufactured by Fusion Co., Ltd.) to form an acrylic layer A having athickness of 2 μm (corresponding to a base material not subjected touniaxial alignment).

The thickness of the acrylic layer A was measured by the followingmethod.

<Film Thickness Measurement>

A part of the formed acrylic layer A was peeled off, and the filmthickness was measured with a 10×objective lens using a profilemeasurement laser microscope VK-X200 (manufactured by KeyenceCorporation).

Preparation of Reflective Layer

The liquid crystal composition shown in Table 1 was applied onto theprepared acrylic layer A using a wire bar to form a composition layer.Next, the composition layer of the liquid crystal composition was driedat room temperature for 50 seconds, and then heated in an atmosphere at95° C. for 1 minute to align the liquid crystal compound (in otherwords, being brought into a cholesteric liquid crystalline phase state).Next, the composition layer in which the liquid crystal compound wasaligned was cooled to 30° C.

Thereafter, with respect to the composition layer in which the liquidcrystal compound was aligned, the coating layer was irradiated withultraviolet rays at 30° C. for 8 seconds using a D bulb (lamp 90 mW/cm²,output 80%, manufactured by Fusion Co., Ltd.) to form a reflective layer(fixed cholesteric liquid crystal layer) having a thickness of 1.6 μm.The thickness of the reflective layer was measured by a method whichwill be described later.

It was confirmed that each of the reflective layers had a reflectionpeak in a wavelength range of 450 to 650 nm.

In addition, the cross-sectional SEM observation of the reflective layerconfirmed that the reflective layer of the Examples gives a stripepattern of a bright portion (continuous line) and a dark portion(continuous line) to have a region in which the angle between the normalof a line formed by at least one dark portion and the surface of the CLlayer periodically or irregularly changes.

Thickness of Reflective Layer

A part of the formed reflective layer was peeled off, and the filmthickness was measured with a 10×objective lens using a profilemeasurement laser microscope VK-X200 (manufactured by KeyenceCorporation).

Various Evaluations

<Evaluation of Diffuse Reflectivity (reflection amount at 45° (“45°reflection amount”))>

In addition, the prepared reflective layer was set facing the lightsource side on a spectrophotometer V-670 (manufactured by JASCOCorporation) equipped with an absolute reflectance measurement system,and the degree of the reflection performance at 45° was evaluated underthe conditions of 0° incidence and 45° detection.

In addition, for the evaluation of the reflection performance at 45°, agraph was plotted by taking the wavelength on the lateral axis and thereflectance on the vertical axis, the reflectance derived from thesubstrate was removed, the area of the reflection peak in a region of450 to 650 nm corresponding to the selective reflection wavelength ofthe reflective layer was calculated, and the size of this area wasevaluated as the reflection amount at 45°.

The reflection amount is preferably 5.0 or more and more preferably 7.0or more.

The results are shown in Table 2.

<Planar Evaluation>

With respect to the composition layer immediately after applicationusing a wire bar, the surface state was visually confirmed under crossednicols, and the planarity was evaluated according to the followingevaluation standards.

In addition, in a case where the evaluation result was “C” or higher, itwas judged as pass. The evaluation result is preferably “B” or higherand more preferably “A”, from the viewpoint of more excellent productionefficiency. The results are shown in Table 2.

(Evaluation Standards)

“A”: “Drying unevenness” and “foreign matter” are not observed.

“B”: “Drying unevenness” or “foreign matter” is slightly observed, butit can be used without any problem.

“C”: “Unevenness due to drying unevenness” or “foreign matter” isslightly observed, but it can be used without any problem.

“D”: “Unevenness due to drying unevenness” or “foreign matter” is oftenobserved, which is thus not suitable for use.

In the following table, “Content of repeating unit represented byGeneral Formula (X1)” is intended to refer to the content (% by mass) ofthe repeating unit containing a group represented by General Formula(X1) with respect to all the repeating units of the specific copolymer.

In the table, “-” shown in the column of “Whether or not Z¹ in GeneralFormula (Y1) is hydrogen atom” is intended to mean that the copolymerused does not contain the “repeating unit represented by General Formula(Yl)”.

In the table, “-” shown in the column of “Content of repeating unitrepresented by General Formula (X1)” is intended to mean that thecopolymer used does not contain the “repeating unit represented byGeneral Formula (X1)”.

TABLE 2 Specific copolymer Whether or Content of Weight- not Z¹ inrepeating unit Type of liquid average General represented by crystalmolecular Formula (Y1) is General Diffuse composition Type weighthydrogen atom Formula (X1) reflectivity Planarity Example 1 Liquidcrystal Copolymer 1-1 5800 Non-hydrogen 37% by mass 7.8 A composition 1atom Example 2 Liquid crystal Copolymer 1-1 5800 Non-hydrogen 37% bymass 8.6 A composition 2 atom Example 3 Liquid crystal Copolymer 1-25200 Non-hydrogen 50% by mass 7.4 A composition 3 atom Example 4 Liquidcrystal Copolymer 1-2 5200 Non-hydrogen 50% by mass 8.2 A composition 4atom Example 5 Liquid crystal Copolymer 1-3 4000 Non-hydrogen 30% bymass 7.4 A composition 5 atom Example 6 Liquid crystal Copolymer 1-46900 Non-hydrogen 30% by mass 7.5 A composition 6 atom Example 7 Liquidcrystal Copolymer 1-5 9200 Non-hydrogen 30% by mass 7.5 B composition 7atom Example 8 Liquid crystal Copolymer 1-6 5200 Non-hydrogen 15% bymass 5.3 C composition 8 atom Example 9 Liquid crystal Copolymer 1-76200 Hydrogen 30% by mass 6.3 A composition 9 atom Example 10 Liquidcrystal Copolymer 1-8 8800 Non-hydrogen 30% by mass 7.8 A composition 10atom Example 11 Liquid crystal Copolymer 1-9 6500 Non-hydrogen 30% bymass 7.7 A composition 11 atom Example 12 Liquid crystal Copolymer 1-105800 Non-hydrogen 40% by mass 7.3 A composition 12 atom ComparativeLiquid crystal — — — — 6.2 D Example 1 composition 13 Comparative Liquidcrystal Copolymer X-1 46000 — — 0.2 A Example 2 composition 14Comparative Liquid crystal Copolymer X-2 5300 Non-hydrogen — 6.8 DExample 3 composition 15 atom Comparative Liquid crystal Copolymer X-333200 Non-hydrogen 30% by mass 6.8 D Example 4 composition 16 atomComparative Liquid crystal Copolymer X-4 23000 — 40% by mass 4.5 BExample 5 composition 17

From the results in Table 2, it was clear that the liquid crystalcompositions of Examples had excellent planarity in a case of beingformed into a coating film and was also capable of forming a reflectivelayer having excellent diffuse reflectivity.

From the comparison between Example 1 and Example 2 and the comparisonbetween Example 3 and Example 4, it was confirmed that the diffusereflectivity of the reflective layer was more excellent by carrying outa step of cooling the composition layer in a cholesteric liquidcrystalline state (corresponding to the step 4) using atemperature-dependent chiral agent.

From the results of Example 7, it was confirmed that the planarity ofthe coating film was further improved in a case where the weight-averagemolecular weight of the specific copolymer was less than 9,000.

From the results of Example 8, it was confirmed that the planarity ofthe coating film was further improved and the reflective layer was moreexcellent in diffuse reflectivity, in a case where the content of therepeating unit containing a group represented by General Formula (X1) inthe specific copolymer was 25% by mass or more with respect to all therepeating units.

From the results of Example 9, it was confirmed that, in the repeatingunit represented by General Formula (Y1) in the specific copolymer, in acase where Z¹ is not a hydrogen atom (in a case where Z¹ is preferablyan alkyl group having 1 to 20 carbon atoms in which —CH₂— may besubstituted with —O—, —CO—O—, —O—CO—, or —CO—O—, —O—CO—, or —CO—, analkenyl group having 2 to 20 carbon atoms in which —CH₂— may besubstituted with —O— or —CO—, a halogen atom, a cyano group, an acetylgroup, a formyl group, a carboxy group, or a hydroxy group), thehorizontal alignment of the liquid crystal compound was suppressed andthe reflective layer was more excellent in diffuse reflectivity.

What is claimed is:
 1. A liquid crystal composition comprising: apolymerizable liquid crystal compound; and a copolymer containing arepeating unit containing a group represented by General Formula (X1)and a repeating unit derived from a monomer represented by GeneralFormula (Y1), and having a weight-average molecular weight of less than10,000:* —L¹¹—CF₂X^(a)   (X1) in General Formula (X1), L¹ represents a singlebond or a perfluoroalkylene group having 1 to 6 carbon atoms which maycontain —O—, X^(a) represents a hydrogen atom or a fluorine atom, and *represents a bonding position, and

in General Formula (Y1), R¹ represents a hydrogen atom or a methylgroup, R² represents —O— or —NR³—, R³ represents a hydrogen atom or analkyl group having 1 to 3 carbon atoms, L^(l) represents an alkylenegroup having 1 to 20 carbon atoms in which —CH₂— may be substituted with—O—, —S—, or —CO—, X¹ and Y¹ each independently represent a single bond,—O—, —CO—O—, —O—CO—, —O—CO—O—, —O—CH₂—, —CH₂O—, —C═N—, —N═C—,—CO—O—CH₂CH₂—, or —CH₂CH₂—CO—O—, A¹ and A² each independently representa phenylene group, a cyclohexylene group, or a naphthylene group, eachof which may have a substituent, Z¹ represents an alkyl group having 1to 20 carbon atoms in which —CH₂— may be substituted with —O—, —CO—O—,—O—CO—, or —CO—, an alkenyl group having 2 to 20 carbon atoms in which—CH₂— may be substituted with —O— or —CO—, a halogen atom, a cyanogroup, an acetyl group, a formyl group, a carboxy group, a hydrogenatom, or a hydroxy group, m represents 0 or 1, n represents an integerof 2 to 4, and a plurality of A¹'s and a plurality of Y¹'s each may bethe same as or different from each other.
 2. The liquid crystalcomposition according to claim 1, wherein a content of the repeatingunit containing a group represented by General Formula (X1) is 25% bymass or more with respect to all the repeating units of the copolymer.3. The liquid crystal composition according to claim 1, wherein therepeating unit containing a group represented by General Formula (X1) isa repeating unit derived from a monomer represented by General Formula(X2):

in General Formula (X2), R¹¹ represents a hydrogen atom or a methylgroup, and R¹² represents a monovalent group containing the grouprepresented by General Formula (X1).
 4. The liquid crystal compositionaccording to claim 1, wherein Z¹ is an alkyl group having 1 to 20 carbonatoms in which —CH₂— may be substituted with —O—, —CO—O—, —OC—O—, or—CO—, an alkenyl group having 2 to 20 carbon atoms in which —CH₂— may besubstituted with —O— or —CO—, a halogen atom, a cyano group, an acetylgroup, a formyl group, a carboxy group, or a hydroxy group.
 5. Theliquid crystal composition according to claim 1, wherein, in GeneralFormula (Y1), A¹ and A² each independently represent a 1,2-phenylenegroup, a 1,3-phenylene group, a 1,4-phenylene group, or a1,4-cyclohexylene group, each of which may have a substituent, X¹represents a single bond, —O—, —CO—O—, or —O—CO—, one or more of Y¹'srepresent —CO—O— or —O—CO—, and Z¹ represents an alkyl group having 1 to8 carbon atoms in which —CH₂— may be substituted with —O—, —CO—O—,—O—CO—, or —CO—, an alkenyl group having 2 to 8 carbon atoms in which—CH₂— may be substituted with —O— or —CO—, a halogen atom, or a cyanogroup.
 6. The liquid crystal composition according to claim 1, wherein acontent of the repeating unit derived from a monomer containing two ormore polymerizable groups in the copolymer is less than 5 mol % withrespect to all the repeating units of the copolymer.
 7. The liquidcrystal composition according to claim 1, wherein the copolymer has aweight-average molecular weight of less than 9,000.
 8. The liquidcrystal composition according to claim 1, wherein a content of thecopolymer is 0.01% by mass or more and less than 5% by mass with respectto a content of the polymerizable liquid crystal compound.
 9. The liquidcrystal composition according to claim 1, further comprising: a chiralagent.
 10. A reflective layer obtained by polymerizing the liquidcrystal composition according to claim
 1. 11. A method for producing areflective layer, comprising: a step 1 of forming a composition layer ona transparent base material not subjected to a uniaxial alignmenttreatment using the liquid crystal composition according to claim 1; astep 2 of aligning a liquid crystal compound contained in thecomposition layer into a cholesteric liquid crystalline phase state; anda step 3 of fixing the cholesteric liquid crystalline phase after thestep
 2. 12. A copolymer comprising: a repeating unit derived from amonomer represented by General Formula (X2); and a repeating unitderived from a monomer represented by General Formula (Y1), wherein thecopolymer has a weight-average molecular weight of less than 10,000:

in General Formula (X2), R¹¹ represents a hydrogen atom or a methylgroup, and R¹² represents a monovalent group containing a grouprepresented by General Formula (X1),* —L¹¹—CF₂X^(a)   (X1) in Formula (X1), L¹¹ represents a single bond ora perfluoroalkylene group having 1 to 6 carbon atoms which may contain—O—, X^(a) represents a hydrogen atom or a fluorine atom, and *represents a bonding position, and

in General Formula (Y1), R¹ represents a hydrogen atom or a methylgroup, R² represents —O— or —NR³—, R³ represents a hydrogen atom or analkyl group having 1 to 3 carbon atoms, L¹ represents an alkylene grouphaving 1 to 20 carbon atoms in which —CH₂— may be substituted with —O—,—S—, or —CO—, X¹ and Y¹ each independently represent a single bond, —O—,—CO—O—, —O—CO—, —O—CO—O—, —O—CH₂—, —CH₂—O—, —C═N—, —N═C—, —CO—O—CH₂CH₂,or —CH₂CH₂—CO—O—, A¹ and A² each independently represent a phenylenegroup, a cyclohexylene group, or a naphthylene group, each of which mayhave a substituent, Z¹ represents an alkyl group having 1 to 20 carbonatoms in which —CH₂— may be substituted with —O—, —CO—O—, —O—CO—, or—CO—, an alkenyl group having 2 to 20 carbon atoms in which —CH₂— may besubstituted with —O——or —CO—, a halogen atom, a cyano group, an acetylgroup, a formyl group, a carboxy group, a hydrogen atom, or a hydroxygroup, m represents 0 or 1, n represents an integer of 2 to 4, and aplurality of A^(l)'s and a plurality of Y¹'s each may be the same as ordifferent from each other.
 13. The liquid crystal composition accordingto claim 1, wherein General Formula (Y1) does not include two or morepolymerizable groups.
 14. The liquid crystal composition according toclaim 1, wherein Z¹ is an alkyl group having 1 to 20 carbon atoms inwhich —CH₂— may be substituted with —O—, —CO—O—, —O—CO—, or —CO—, ahalogen atom, a cyano group, an acetyl group, a formyl group, a carboxygroup, a hydrogen atom or a hydroxy group.
 15. The copolymer accordingto claim 12, p1 wherein General Formula (Y1) does not include two ormore polymerizable groups.
 16. The copolymer according to claim 12,wherein Z¹ is an alkyl group having 1 to 20 carbon atoms in which —CH₂—may be substituted with —O—, —CO—O—, —O—CO—, or —CO—, a halogen atom, acyano group, an acetyl group, a formyl group, a carboxy group, ahydrogen atom or a hydroxy group.
 17. The liquid crystal compositionaccording to claim 2, wherein the repeating unit containing a grouprepresented by General Formula (X1) is a repeating unit derived from amonomer represented by General Formula (X2):

in General Formula (X2), R¹¹ represents a hydrogen atom or a methylgroup, and R¹² represents a monovalent group containing the grouprepresented by General Formula (X1).
 18. The liquid crystal compositionaccording to claim 2, wherein Z¹ is an alkyl group having 1 to 20 carbonatoms in which —CH₂— may be substituted with —O—, —CO—O—, —O—CO—, or—CO—, an alkenyl group having 2 to 20 carbon atoms in which —CH₂— may besubstituted with —O— or—CO—, a halogen atom, a cyano group, an acetylgroup, a formyl group, a carboxy group, or a hydroxy group.
 19. Theliquid crystal composition according to claim 3, wherein Z¹ is an alkylgroup having 1 to 20 carbon atoms in which —CH₂— may be substituted with—O—, —CO—O—, —O—CO—, or —CO—, an alkenyl group having 2 to 20 carbonatoms in which —CH₂— may be substituted with —O— or —CO—, a halogenatom, a cyano group, an acetyl group, a formyl group, a carboxy group,or a hydroxy group.
 20. The liquid crystal composition according toclaim 2, wherein, in General Formula (Y1), A¹ and A² each independentlyrepresent a 1,2-phenylene group, a 1,3-phenylene group, a 1,4-phenylenegroup, or a 1,4-cyclohexylene group, each of which may have asubstituent, X¹ represents a single bond, —O—, —CO—O—, or —O—CO—, one ormore of Y¹'s represent —CO—O— or —O—CO—, and Z¹ represents an alkylgroup having 1 to 8 carbon atoms in which —CH₂— may be substituted with—O—, —CO—O—, —O—CO—, or —CO—, an alkenyl group having 2 to 8 carbonatoms in which —CH₂— may be substituted with —O— or —C—, a halogen atom,or a cyano group.